WorldWideScience

Sample records for wave heating efficiency

  1. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and ... having trouble with the heat. If a heat wave is predicted or happening… - Slow down. Avoid strenuous ...

  2. Efficient heat generation in large-area graphene films by electromagnetic wave absorption

    Science.gov (United States)

    Kang, Sangmin; Choi, Haehyun; Lee, Soo Bin; Park, Seong Chae; Park, Jong Bo; Lee, Sangkyu; Kim, Youngsoo; Hong, Byung Hee

    2017-06-01

    Graphene has been intensively studied due to its outstanding electrical and thermal properties. Recently, it was found that the heat generation by Joule heating of graphene is limited by the conductivity of graphene. Here we suggest an alternative method to generate heat on a large-area graphene film more efficiently by utilizing the unique electromagnetic (EM) wave absorption property of graphene. The EM wave induces an oscillating magnetic moment generated by the orbital motion of moving electrons, which efficiently absorbs the EM energy and dissipate it as a thermal energy. In this case, the mobility of electron is more important than the conductivity, because the EM-induced diamagnetic moment is directly proportional to the speed of electron in an orbital motion. To control the charge carrier mobility of graphene we functionalized substrates with self-assembled monolayers (SAM). As the result, we find that the graphene showing the Dirac voltage close to zero can be more efficiently heated by EM waves. In addition, the temperature gradient also depends on the number of graphene. We expect that the efficient and fast heating of graphene films by EM waves can be utilized for smart heating windows and defogging windshields.

  3. Efficient Wave Energy Amplification with Wave Reflectors

    OpenAIRE

    Kramer, Morten Mejlhede; Frigaard, Peter Bak

    2002-01-01

    Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified ...

  4. Urban Heat Wave Hazard Assessment

    Science.gov (United States)

    Quattrochi, D. A.; Jedlovec, G.; Crane, D. L.; Meyer, P. J.; LaFontaine, F.

    2016-12-01

    Heat waves are one of the largest causes of environmentally-related deaths globally and are likely to become more numerous as a result of climate change. The intensification of heat waves by the urban heat island effect and elevated humidity, combined with urban demographics, are key elements leading to these disasters. Better warning of the potential hazards may help lower risks associated with heat waves. Moderate resolution thermal data from NASA satellites is used to derive high spatial resolution estimates of apparent temperature (heat index) over urban regions. These data, combined with demographic data, are used to produce a daily heat hazard/risk map for selected cities. MODIS data are used to derive daily composite maximum and minimum land surface temperature (LST) fields to represent the amplitude of the diurnal temperature cycle and identify extreme heat days. Compositing routines are used to generate representative daily maximum and minimum LSTs for the urban environment. The limited effect of relative humidity on the apparent temperature (typically 10-15%) allows for the use of modeled moisture fields to convert LST to apparent temperature without loss of spatial variability. The daily max/min apparent temperature fields are used to identify abnormally extreme heat days relative to climatological values in order to produce a heat wave hazard map. Reference to climatological values normalizes the hazard for a particular region (e.g., the impact of an extreme heat day). A heat wave hazard map has been produced for several case study periods and then computed on a quasi-operational basis during the summer of 2016 for Atlanta, GA, Chicago, IL, St. Louis, MO, and Huntsville, AL. A hazard does not become a risk until someone or something is exposed to that hazard at a level that might do harm. Demographic information is used to assess the urban risk associated with the heat wave hazard. Collectively, the heat wave hazard product can warn people in urban

  5. Efficient Wave Energy Amplification with Wave Reflectors

    DEFF Research Database (Denmark)

    Kramer, Morten Mejlhede; Frigaard, Peter Bak

    2002-01-01

    Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130......-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power benifit...... for different geometries of the wave reflectors and optimal geometrical design parameters are specified. On this basis inventors of WEC's can evaluate whether a specific WEC possible could benefit from wave reflectors....

  6. ELF wave generation in the ionosphere using pulse modulated HF heating: initial tests of a technique for increasing ELF wave generation efficiency

    Directory of Open Access Journals (Sweden)

    R. Barr

    1999-06-01

    Full Text Available This paper describes the results of a preliminary study to determine the effective heating and cooling time constants of ionospheric currents in a simulated modulated HF heating, `beam painting' configuration. It has been found that even and odd harmonics of the fundamental ELF wave used to amplitude modulate the HF heater are sourced from different regions of the ionosphere which support significantly different heating and cooling time constants. The fundamental frequency and its odd harmonics are sourced in a region of the ionosphere where the heating and cooling time constants are about equal. The even harmonics on the other hand are sourced from regions of the ionosphere characterised by ratios of cooling to heating time constant greater than ten. It is thought that the even harmonics are sourced in the lower ionosphere (around 65 km where the currents are much smaller than at the higher altitudes around 78 km where the currents at the fundamental frequency and odd harmonics maximise.Key words. Electromagnetics (antennae · Ionosphere (active experiments · Radio science (non linear phenomena

  7. Ion Bernstein wave heating research

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Masayuki.

    1992-03-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW's low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW's that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW's can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.

  8. Ion Bernstein wave heating research

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Masayuki

    1992-03-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW`s low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much_lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW`s that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW`s can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.

  9. The theory of magnetohydrodynamic wave generation by localized sources. III - Efficiency of plasma heating by dissipation of far-field waves. [in solar corona

    Science.gov (United States)

    Collins, William

    1992-01-01

    The fraction of radiation emitted by Alfven waves is calculated by using two separate methods to determine whether the Alfven flux generated in the photosphere is sufficient to heat the corona. One method employs a set of scaling laws for the fluxes as functions of plasma and source parameters; the second method consist of a procedure for calculating the flux in each waveband from the interaction of vector-harmonic components of an arbitrary applied forcing. Both methods indicate that the Alfven flux accounts roughly for half of the total emission. The need to reexamine estimates of the amount of Alfven flux reaching the corona based on observations of plasma disturbances in the photosphere is emphasized.

  10. Heat Waves in the United States: Mortality Risk during Heat Waves and Effect Modification by Heat Wave Characteristics in 43 U.S. Communities

    Science.gov (United States)

    Anderson, G. Brooke; Bell, Michelle L.

    2011-01-01

    Background Devastating health effects from recent heat waves, and projected increases in frequency, duration, and severity of heat waves from climate change, highlight the importance of understanding health consequences of heat waves. Objectives We analyzed mortality risk for heat waves in 43 U.S. cities (1987–2005) and investigated how effects relate to heat waves’ intensity, duration, or timing in season. Methods Heat waves were defined as ≥ 2 days with temperature ≥ 95th percentile for the community for 1 May through 30 September. Heat waves were characterized by their intensity, duration, and timing in season. Within each community, we estimated mortality risk during each heat wave compared with non-heat wave days, controlling for potential confounders. We combined individual heat wave effect estimates using Bayesian hierarchical modeling to generate overall effects at the community, regional, and national levels. We estimated how heat wave mortality effects were modified by heat wave characteristics (intensity, duration, timing in season). Results Nationally, mortality increased 3.74% [95% posterior interval (PI), 2.29–5.22%] during heat waves compared with non-heat wave days. Heat wave mortality risk increased 2.49% for every 1°F increase in heat wave intensity and 0.38% for every 1-day increase in heat wave duration. Mortality increased 5.04% (95% PI, 3.06–7.06%) during the first heat wave of the summer versus 2.65% (95% PI, 1.14–4.18%) during later heat waves, compared with non-heat wave days. Heat wave mortality impacts and effect modification by heat wave characteristics were more pronounced in the Northeast and Midwest compared with the South. Conclusions We found higher mortality risk from heat waves that were more intense or longer, or those occurring earlier in summer. These findings have implications for decision makers and researchers estimating health effects from climate change. PMID:21084239

  11. Humid heat waves at different warming levels.

    Science.gov (United States)

    Russo, Simone; Sillmann, Jana; Sterl, Andreas

    2017-08-07

    The co-occurrence of consecutive hot and humid days during a heat wave can strongly affect human health. Here, we quantify humid heat wave hazard in the recent past and at different levels of global warming. We find that the magnitude and apparent temperature peak of heat waves, such as the ones observed in Chicago in 1995 and China in 2003, have been strongly amplified by humidity. Climate model projections suggest that the percentage of area where heat wave magnitude and peak are amplified by humidity increases with increasing warming levels. Considering the effect of humidity at 1.5° and 2° global warming, highly populated regions, such as the Eastern US and China, could experience heat waves with magnitude greater than the one in Russia in 2010 (the most severe of the present era). The apparent temperature peak during such humid-heat waves can be greater than 55 °C. According to the US Weather Service, at this temperature humans are very likely to suffer from heat strokes. Humid-heat waves with these conditions were never exceeded in the present climate, but are expected to occur every other year at 4° global warming. This calls for respective adaptation measures in some key regions of the world along with international climate change mitigation efforts.

  12. Recovering waste industrial heat efficiently

    Energy Technology Data Exchange (ETDEWEB)

    Hnat, J.G.; Bartone, L.M.; Cutting, J.C.; Patten, J.S.

    1983-03-01

    Organic Rankine Cycles (ORC's) are being used in the generation of electrical or mechanical power in situations where little demand exists for process steam. Using organic fluids in Rankine cycles improves the potential for economic recovery of waste heat. The right organic fluid can enhance the conversion efficiency by tailoring the ORC heat recovery cycle to the thermodynamic characteristics of the waste heat stream. The selection of the working fluid is affected by its flammability, toxicity, environmental impact, materials compatibility, and cost. Water, ethanol, 2-methyl Pyridine/H2O, Flourinol, Toluene, Freon R-11, and Freon R-113 are compared. An organic cycle using toluene as the working fluid is schematicized.

  13. Efficient transformer for electromagnetic waves

    Science.gov (United States)

    Miller, R.B.

    A transformer structure for efficient transfer of electromagnetic energy from a transmission line to an unmatched load provides voltage multiplication and current division by a predetermined constant. Impedance levels are transformed by the square of that constant. The structure includes a wave splitter, connected to an input transmission device and to a plurality of output transmission devices. The output transmission devices are effectively connected in parallel to the input transmission device. The output transmission devices are effectively series connected to provide energy to a load. The transformer structure is particularly effective in increasing efficiency of energy transfer through an inverting convolute structure by capturing and transferring energy losses from the inverter to the load.

  14. Wave Heating of the Solar Chromosphere

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The nonmagnetic interior of supergranulation cells has been thought since the 1940s to be heated by the dissipation of acoustic waves. But all attempts to measure the acoustic flux have failed to show sufficient energy for chromospheric heating. Recent space observations with TRACE, for example, have ...

  15. Wave heating of the solar atmosphere.

    Science.gov (United States)

    Arregui, Iñigo

    2015-05-28

    Magnetic waves are a relevant component in the dynamics of the solar atmosphere. Their significance has increased because of their potential as a remote diagnostic tool and their presumed contribution to plasma heating processes. We discuss our current understanding of coronal heating by magnetic waves, based on recent observational evidence and theoretical advances. The discussion starts with a selection of observational discoveries that have brought magnetic waves to the forefront of the coronal heating discussion. Then, our theoretical understanding of the nature and properties of the observed waves and the physical processes that have been proposed to explain observations are described. Particular attention is given to the sequence of processes that link observed wave characteristics with concealed energy transport, dissipation and heat conversion. We conclude with a commentary on how the combination of theory and observations should help us to understand and quantify magnetic wave heating of the solar atmosphere. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  16. Chiral heat wave and mixing of magnetic, vortical and heat waves in chiral media

    Energy Technology Data Exchange (ETDEWEB)

    Chernodub, M.N. [CNRS, Laboratoire de Mathématiques et Physique Théorique,Université de Tours, 37200 (France); Soft Matter Physics Laboratory, Far Eastern Federal University,Sukhanova 8, Vladivostok (Russian Federation); Department of Physics and Astronomy, University of Gent,Krijgslaan 281, S9, Gent (Belgium)

    2016-01-18

    We show that a hot rotating fluid of relativistic chiral fermions possesses a new gapless collective mode associated with coherent propagation of energy density and chiral density waves along the axis of rotation. This mode, which we call the Chiral Heat Wave, emerges due to a mixed gauge-gravitational anomaly. At finite density the Chiral Heat Wave couples to the Chiral Vortical Wave while in the presence of an external magnetic field it mixes with the Chiral Magnetic Wave. The coupling of the Chiral Magnetic and Chiral Vortical Waves is also demonstrated. We find that the coupled waves — which are coherent fluctuations of the vector, axial and energy currents — have generally different velocities compared to the velocities of the individual waves.

  17. Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Green, David L [ORNL; Jaeger, E. F. [XCEL; Berry, Lee A [ORNL; Chen, Guangye [ORNL; Ryan, Philip Michael [ORNL; Canik, John [ORNL

    2011-01-01

    Observations of improved radio frequency (RF) heating efficiency in high-confinement (H-) mode plasmas on the National Spherical Tokamak Experiment (NSTX) are investigated by whole-device linear simulation. We present the first full-wave simulation to couple kinetic physics of the well confined core plasma to the poorly confined scrape-off plasma. The new simulation is used to scan the launched fast-wave spectrum and examine the steady-state electric wave field structure for experimental scenarios corresponding to both reduced, and improved RF heating efficiency. We find that launching toroidal wave-numbers that required for fast-wave propagation excites large amplitude (kVm 1 ) coaxial standing modes in the wave electric field between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggest these modes are a probable cause of degraded heating efficiency. Also, the H-mode density pedestal and fast-wave cutoff within the confined plasma allow for the excitation of whispering gallery type eigenmodes localised to the plasma edge.

  18. Climate Change Effects on Heat Waves and Future Heat Wave-Associated IHD Mortality in Germany

    Directory of Open Access Journals (Sweden)

    Stefan Zacharias

    2014-12-01

    Full Text Available The influence of future climate change on the occurrence of heat waves and its implications for heat wave-related mortality due to ischemic heart diseases (IHD in Germany is studied. Simulations of 19 regional climate models with a spatial resolution of 0.25° × 0.25° forced by the moderate climate change scenario A1B are analyzed. Three model time periods of 30 years are evaluated, representing present climate (1971–2000, near future climate (2021–2050, and remote future climate (2069–2098. Heat waves are defined as periods of at least three consecutive days with daily mean air temperature above the 97.5th percentile of the all-season temperature distribution. Based on the model simulations, future heat waves in Germany will be significantly more frequent, longer lasting and more intense. By the end of the 21st century, the number of heat waves will be tripled compared to present climate. Additionally, the average duration of heat waves will increase by 25%, accompanied by an increase of the average temperature during heat waves by about 1 K. Regional analyses show that stronger than average climate change effects are observed particularly in the southern regions of Germany. Furthermore, we investigated climate change impacts on IHD mortality in Germany applying temperature projections from 19 regional climate models to heat wave mortality relationships identified in a previous study. Future IHD excess deaths were calculated both in the absence and presence of some acclimatization (i.e., that people are able to physiologically acclimatize to enhanced temperature levels in the future time periods by 0% and 50%, respectively. In addition to changes in heat wave frequency, we incorporated also changes in heat wave intensity and duration into the future mortality evaluations. The results indicate that by the end of the 21st century the annual number of IHD excess deaths in Germany attributable to heat waves is expected to rise by factor 2

  19. Northern Eurasian Heat Waves and Droughts

    Science.gov (United States)

    Schubert, Siegfried; Wang, Hailan; Koster, Randal; Suarez, Max; Groisman, Pavel

    2013-01-01

    This article reviews our understanding of the characteristics and causes of northern Eurasian summertime heat waves and droughts. Additional insights into the nature of temperature and precipitation variability in Eurasia on monthly to decadal time scales and into the causes and predictability of the most extreme events are gained from the latest generation of reanalyses and from supplemental simulations with the NASA GEOS-5 AGCM. Key new results are: 1) the identification of the important role of summertime stationary Rossby waves in the development of the leading patterns of monthly Eurasian surface temperature and precipitation variability (including the development of extreme events such as the 2010 Russian heat wave), 2) an assessment of the mean temperature and precipitation changes that have occurred over northern Eurasia in the last three decades and their connections to decadal variability and global trends in SST, and 3) the quantification (via a case study) of the predictability of the most extreme simulated heat wave/drought events, with some focus on the role of soil moisture in the development and maintenance of such events. A literature survey indicates a general consensus that the future holds an enhanced probability of heat waves across northern Eurasia, while there is less agreement regarding future drought, reflecting a greater uncertainty in soil moisture and precipitation projections. Substantial uncertainties remain in our understanding of heat waves and drought, including the nature of the interactions between the short-term atmospheric variability associated with such extremes and the longer-term variability and trends associated with soil moisture feedbacks, SST anomalies, and an overall warming world.

  20. Mounting for diodes provides efficient heat sink

    Science.gov (United States)

    1964-01-01

    Efficient heat sink is provided by soldering diodes to metal support bars which are brazed to a ceramic base. Electrical connections between diodes on adjacent bars are made flexible by metal strips which aid in heat dissipation.

  1. Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas.

    Science.gov (United States)

    Green, D L; Berry, L A; Chen, G; Ryan, P M; Canik, J M; Jaeger, E F

    2011-09-30

    Observations of improved radio frequency (rf) heating efficiency in ITER relevant high-confinement (H-)mode plasmas on the National Spherical Tokamak Experiment are investigated by whole-device linear simulation. The steady-state rf electric field is calculated for various antenna spectra and the results examined for characteristics that correlate with observations of improved or reduced rf heating efficiency. We find that launching toroidal wave numbers that give fast-wave propagation in the scrape-off plasma excites large amplitude (∼kV m(-1)) coaxial standing modes between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggests that these modes are a probable cause of degraded heating efficiency.

  2. Was there a basis for anticipating the 2010 Russian heat wave?: THE 2010 RUSSIAN HEAT WAVE

    National Research Council Canada - National Science Library

    Dole, Randall; Hoerling, Martin; Perlwitz, Judith; Eischeid, Jon; Pegion, Philip; Zhang, Tao; Quan, Xiao-Wei; Xu, Taiyi; Murray, Donald

    2011-01-01

      The 2010 summer heat wave in western Russia was extraordinary, with the region experiencing the warmest July since at least 1880 and numerous locations setting all-time maximum temperature records...

  3. Heat Wave Vulnerability Mapping for India.

    Science.gov (United States)

    Azhar, Gulrez; Saha, Shubhayu; Ganguly, Partha; Mavalankar, Dileep; Madrigano, Jaime

    2017-03-30

    Assessing geographic variability in heat wave vulnerability forms the basis for planning appropriate targeted adaptation strategies. Given several recent deadly heatwaves in India, heat is increasingly being recognized as a public health problem. However, to date there has not been a country-wide assessment of heat vulnerability in India. We evaluated demographic, socioeconomic, and environmental vulnerability factors and combined district level data from several sources including the most recent census, health reports, and satellite remote sensing data. We then applied principal component analysis (PCA) on 17 normalized variables for each of the 640 districts to create a composite Heat Vulnerability Index (HVI) for India. Of the total 640 districts, our analysis identified 10 and 97 districts in the very high and high risk categories (> 2SD and 2-1SD HVI) respectively. Mapping showed that the districts with higher heat vulnerability are located in the central parts of the country. On examination, these are less urbanized and have low rates of literacy, access to water and sanitation, and presence of household amenities. Therefore, we concluded that creating and mapping a heat vulnerability index is a useful first step in protecting the public from the health burden of heat. Future work should incorporate heat exposure and health outcome data to validate the index, as well as examine sub-district levels of vulnerability.

  4. Sampling extreme heat waves using a large deviation algorithm

    Science.gov (United States)

    Bouchet, Freddy; Ragone, Francesco; Wouters, Jeroen

    2017-04-01

    For some aspects of climate dynamics, rare dynamical events may play a key role. A class of such problems are extreme events that have huge impacts, for instance extreme heat waves. The study of those events from numerical models is extremely difficult because of the rareness of the event and the related numerical cost. This makes detection and attribution study in this context even more difficult as factual and counterfactual studies have to be sampled through prohibitively long simulations, in order to be compared. In the recent past, new theoretical and numerical tools have been developed in the statistical mechanics community, in order to specifically study such rare events. Those approaches are based on large deviation theory for complex dynamical systems. We will present some of these tools and apply them to a paradigmatic example in climate dynamics: we will study the probability of extreme heat waves over Europe, in a comprehensive climate model. We will demonstrate that large deviation algorithms allow to sample extremely efficiently extreme heat waves. The number of sampled extreme heat waves is increased by a factor of a few hundreds to a thousand, for a given numerical cost, compared to direct numerical simulations. We discuss the future implications for detection and attribution studies.

  5. Energy efficient ammonia heat pump. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Madsen, Claus; Pijnenburg, B.; Schumann Grindorf, H. [Danish Technological Institute, Aarhus (Denmark); Christensen, Rolf [Alfa Laval, Lund (Sweden); Rasmussen, Bjarne D. [Grundfos, Bjerringbro (Denmark); Gram, S.; Fredborg Jakobsen, D. [Svedan Industri Koeleanlaeg, Greve (Denmark)

    2013-09-15

    The report describes the development of a highly effective ammonia heat pump. Heat pumps play an increasingly important role in the search for more effective use of energy in our society. Highly efficient heat pumps can contribute to reduced energy consumption and improved economy of the systems which they are a part of. An ammonia heat pump with high pressure reciprocating compressor and a novel split condenser was developed to prove potential for efficiency optimization. The split of the condenser in two parts can be utilized to obtain smaller temperature approaches and, thereby, improved heat pump efficiency at an equal heat exchanger area, when compared to the traditional solution with separate condenser and de-superheater. The split condenser design can also be exploited for heating a significant share of the total heating capacity to a temperature far above the condensing temperature. Furthermore, the prototype heat pump was equipped with a plate type evaporator combined with a U-turn separator with a minimum liquid height and a liquid pump with the purpose of creating optimum liquid circulation ratio for the highest possible heat transfer coefficients at the lowest possible pressure drop. The test results successfully confirmed the highest possible efficiency; a COP of 4.3 was obtained when heating water from 40 deg. C to 80 deg. C while operating with evaporating/condensing temperatures of +20 deg C/+73 deg C. (Author)

  6. Bulk ion heating with ICRF waves in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Mantsinen, M. J., E-mail: mervi.mantsinen@bsc.es [Catalan Institution for Research and Advanced Studies, Barcelona (Spain); Barcelona Supercomputing Center, Barcelona (Spain); Bilato, R.; Bobkov, V. V.; Kappatou, A.; McDermott, R. M.; Odstrčil, T.; Tardini, G.; Bernert, M.; Dux, R.; Maraschek, M.; Noterdaeme, J.-M.; Ryter, F.; Stober, J. [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Nocente, M. [Dipartimento di Fisica “G. Occhialini”, Università degli Studi di Milano-Bicocca, Milano (Italy); Istituto di Fisica del Plasma “P. Caldirola”, CNR, Milano (Italy); Hellsten, T. [Dept. of Fusion Plasma Physics, EES, KTH, Stockholm (Sweden); Mantica, P.; Tardocchi, M. [Istituto di Fisica del Plasma “P. Caldirola”, CNR, Milano (Italy); Nielsen, S. K.; Rasmussen, J.; Stejner, M. [Technical University of Denmark, Department of Physics, Lyngby (Denmark); and others

    2015-12-10

    Heating with ICRF waves is a well-established method on present-day tokamaks and one of the heating systems foreseen for ITER. However, further work is still needed to test and optimize its performance in fusion devices with metallic high-Z plasma facing components (PFCs) in preparation of ITER and DEMO operation. This is of particular importance for the bulk ion heating capabilities of ICRF waves. Efficient bulk ion heating with the standard ITER ICRF scheme, i.e. the second harmonic heating of tritium with or without {sup 3}He minority, was demonstrated in experiments carried out in deuterium-tritium plasmas on JET and TFTR and is confirmed by ICRF modelling. This paper focuses on recent experiments with {sup 3}He minority heating for bulk ion heating on the ASDEX Upgrade (AUG) tokamak with ITER-relevant all-tungsten PFCs. An increase of 80% in the central ion temperature T{sub i} from 3 to 5.5 keV was achieved when 3 MW of ICRF power tuned to the central {sup 3}He ion cyclotron resonance was added to 4.5 MW of deuterium NBI. The radial gradient of the T{sub i} profile reached locally values up to about 50 keV/m and the normalized logarithmic ion temperature gradients R/LT{sub i} of about 20, which are unusually large for AUG plasmas. The large changes in the T{sub i} profiles were accompanied by significant changes in measured plasma toroidal rotation, plasma impurity profiles and MHD activity, which indicate concomitant changes in plasma properties with the application of ICRF waves. When the {sup 3}He concentration was increased above the optimum range for bulk ion heating, a weaker peaking of the ion temperature profile was observed, in line with theoretical expectations.

  7. Large Efficient Intelligent Heating Relay Station System

    Science.gov (United States)

    Wu, C. Z.; Wei, X. G.; Wu, M. Q.

    2017-12-01

    The design of large efficient intelligent heating relay station system aims at the improvement of the existing heating system in our country, such as low heating efficiency, waste of energy and serious pollution, and the control still depends on the artificial problem. In this design, we first improve the existing plate heat exchanger. Secondly, the ATM89C51 is used to control the whole system and realize the intelligent control. The detection part is using the PT100 temperature sensor, pressure sensor, turbine flowmeter, heating temperature, detection of user end liquid flow, hydraulic, and real-time feedback, feedback signal to the microcontroller through the heating for users to adjust, realize the whole system more efficient, intelligent and energy-saving.

  8. Impacts of the 2015 Heat Waves on Mortality in the Czech Republic—A Comparison with Previous Heat Waves

    Science.gov (United States)

    Urban, Aleš; Hanzlíková, Hana; Kyselý, Jan; Plavcová, Eva

    2017-01-01

    This study aimed to assess the impacts of heat waves during the summer of 2015 on mortality in the Czech Republic and to compare them with those of heat waves back to the previous record-breaking summer of 1994. We analyzed daily natural-cause mortality across the country’s entire population. A mortality baseline was determined using generalized additive models adjusted for long-term trends, seasonal and weekly cycles, and identified heat waves. Mortality deviations from the baseline were calculated to quantify excess mortality during heat waves, defined as periods of at least three consecutive days with mean daily temperature higher than the 95th percentile of annual distribution. The summer of 2015 was record-breaking in the total duration of heat waves as well as their total heat load. Consequently, the impact of the major heat wave in 2015 on the increase in excess mortality relative to the baseline was greater than during the previous record-breaking heat wave in 1994 (265% vs. 240%). Excess mortality was comparable among the younger age group (0–64 years) and the elderly (65+ years) in the 1994 major heat wave while it was significantly larger among the elderly in 2015. The results suggest that the total heat load of a heat wave needs to be considered when assessing its impact on mortality, as the cumulative excess heat factor explains the magnitude of excess mortality during a heat wave better than other characteristics such as duration or average daily mean temperature during the heat wave. Comparison of the mortality impacts of the 2015 and 1994 major heat waves suggests that the recently reported decline in overall heat-related mortality in Central Europe has abated and simple extrapolation of the trend would lead to biased conclusions even for the near future. Further research is needed toward understanding the additional mitigation measures required to prevent heat-related mortality in the Czech Republic and elsewhere. PMID:29236040

  9. Impacts of the 2015 Heat Waves on Mortality in the Czech Republic-A Comparison with Previous Heat Waves.

    Science.gov (United States)

    Urban, Aleš; Hanzlíková, Hana; Kyselý, Jan; Plavcová, Eva

    2017-12-13

    This study aimed to assess the impacts of heat waves during the summer of 2015 on mortality in the Czech Republic and to compare them with those of heat waves back to the previous record-breaking summer of 1994. We analyzed daily natural-cause mortality across the country's entire population. A mortality baseline was determined using generalized additive models adjusted for long-term trends, seasonal and weekly cycles, and identified heat waves. Mortality deviations from the baseline were calculated to quantify excess mortality during heat waves, defined as periods of at least three consecutive days with mean daily temperature higher than the 95th percentile of annual distribution. The summer of 2015 was record-breaking in the total duration of heat waves as well as their total heat load. Consequently, the impact of the major heat wave in 2015 on the increase in excess mortality relative to the baseline was greater than during the previous record-breaking heat wave in 1994 (265% vs. 240%). Excess mortality was comparable among the younger age group (0-64 years) and the elderly (65+ years) in the 1994 major heat wave while it was significantly larger among the elderly in 2015. The results suggest that the total heat load of a heat wave needs to be considered when assessing its impact on mortality, as the cumulative excess heat factor explains the magnitude of excess mortality during a heat wave better than other characteristics such as duration or average daily mean temperature during the heat wave. Comparison of the mortality impacts of the 2015 and 1994 major heat waves suggests that the recently reported decline in overall heat-related mortality in Central Europe has abated and simple extrapolation of the trend would lead to biased conclusions even for the near future. Further research is needed toward understanding the additional mitigation measures required to prevent heat-related mortality in the Czech Republic and elsewhere.

  10. Development of a spinning wave heat engine

    Science.gov (United States)

    Zinn, B. T.; Powell, E. A.; Hubbartt, J. E.

    1982-01-01

    A theoretical analysis and an experimental investigation were conducted to assess the feasibility of developing a spinning wave heat engine. Such as engine would utilize a large amplitude traveling acoustic wave rotating around a cylindrica chamber, and it should not suffer from the inefficiency, noise, and intermittent thrust which characterizes pulse jet engines. The objective of this investigation was to determine whether an artificially driven large amplitude spinning transverse wave could induce a steady flow of air through the combustion chamber under cold flow conditions. In the theoretical analysis the Maslen and Moore perturbation technique was extended to study flat cylinders (pancake geometry) with completely open side walls and a central opening. In the parallel experimental study, a test moel was used to determine resonant frequencies and radial pressure distributions, as well as oscillatory and steady flow velocities at the inner and outer peripheries. The experimental frequency was nearly the same as the theoretical acoustic value for a model of the same outer diameter but without a central hole. Although the theoretical analysis did not predict a steady velocity component, simulaneous measurements of hotwire and microphone responses have shown that the spinning wave pumps a mean flow radially outward through the cavity.

  11. Observation of Electron Bernstein Wave Heating in the RFP

    Science.gov (United States)

    Seltzman, Andrew; Anderson, Jay; Goetz, John; Forest, Cary

    2017-10-01

    The first observation of RF heating in a reversed field pinch (RFP) using the electron Bernstein wave (EBW) has been demonstrated on MST. Efficient mode conversion of an outboard-launched X mode wave at 5.5 GHz leads to Doppler-shifted resonant absorption (ωrf = nωce-k||v||) for a broad range (n =1-7) of harmonics. The dynamics of EBW-heated electrons are measured using a spatial distribution of solid targets with diametrically opposed x-ray detectors. EBW heating produces a clear supra-thermal electron tail in MST. Radial deposition of the EBW is controlled with |B|and is measured using the HXR flux emitted from an insertable probe. In the thick-shelled MST RFP, the radial accessibility of EBW is limited to r/a >0.8 ( 10cm) by magnetic field error induced by the porthole necessary for the antenna. Experimental measurements show EBW propagation inward through a stochastic magnetic field. EBW-heated test electrons are used as a direct probe of edge (r/a >0.9) radial transport, showing a modest transition from `standard' to reduced-tearing RFP operation. Electron loss is too fast for collisional effects and implies a large non-collisional radial diffusivity. EBW heating has been demonstrated in reduced magnetic stochasticity plasmas with β = 15-20%. Work supported by USDOE.

  12. Plasma heating via electron Bernstein wave heating using ordinary and extraodinary mode

    Directory of Open Access Journals (Sweden)

    A. Parvazian

    2008-03-01

    Full Text Available Magnetically confined plasma can be heated with high power microwave sources. In spherical torus the electron plasma frequency exeeds the electron cyclotron frequency (EC and, as a consequence, electromagnetic waves at fundamental and low harmonic EC cannot propagate within the plasma. In contrast, electron Bernstein waves (EBWs readily propagate in spherical torus plasma and are absorbed strongly at the electron cyclotron resonances. In order to proagate EBWs beyond the upper hybrid resonance (UHR, that surrounds the plasma, the EBWs must convert via one of two processes to either ordinary (O-mode or extraordinary (X-mode electromagnetic waves. O-mode and X-mode electromagnetic waves lunched at the plasma edge can convert to the electron Bernstein waves (EBWs which can propagate without and cut-off into the core of the plasma and damp on electrons. Since the electron Bernstein wave (EBW has no cut-off limits, it is well suited to heat an over-dense plasma by resonant absorption. An important problem is to calculate mode conversion coefficient that is very sensitive to density. Mode conversion coefficient depends on Budden parameter ( ñ and density scale length (Ln in upper hybrid resonance (UHR. In Mega Ampere Spherical Tokamak (MAST, the optimized conversion efficiency approached 72.5% when Ln was 4.94 cm and the magnetic field was 0.475 Tesla in the core of the plasma.

  13. The impact of heat waves on surface urban heat island and local economy in Cluj-Napoca city, Romania

    Science.gov (United States)

    Herbel, Ioana; Croitoru, Adina-Eliza; Rus, Adina Viorica; Roşca, Cristina Florina; Harpa, Gabriela Victoria; Ciupertea, Antoniu-Flavius; Rus, Ionuţ

    2017-07-01

    The association between heat waves and the urban heat island effect can increase the impact on environment and society inducing biophysical hazards. Heat stress and their associated public health problems are among the most frequent. This paper explores the heat waves impact on surface urban heat island and on the local economy loss during three heat periods in Cluj-Napoca city in the summer of 2015. The heat wave events were identified based on daily maximum temperature, and they were divided into three classes considering the intensity threshold: moderate heat waves (daily maximum temperature exceeding the 90th percentile), severe heat waves (daily maximum temperature over the 95th percentile), and extremely severe heat waves (daily maximum temperature exceeding the 98th percentile). The minimum length of an event was of minimum three consecutive days. The surface urban heat island was detected based on land surface temperature derived from Landsat 8 thermal infrared data, while the economic impact was estimated based on data on work force structure and work productivity in Cluj-Napoca derived from the data released by Eurostat, National Bank of Romania, and National Institute of Statistics. The results indicate that the intensity and spatial extension of surface urban heat island could be governed by the magnitude of the heat wave event, but due to the low number of satellite images available, we should consider this information only as preliminary results. Thermal infrared remote sensing has proven to be a very efficient method to study surface urban heat island, due to the fact that the synoptic conditions associated with heat wave events usually favor cloud free image. The resolution of the OLI_TIRS sensor provided good results for a mid-extension city, but the low revisiting time is still a drawback. The potential economic loss was calculated for the working days during heat waves and the estimated loss reached more than 2.5 mil. EUR for each heat wave day

  14. Heat Wave and Mortality: A Multicountry, Multicommunity Study.

    Science.gov (United States)

    Guo, Yuming; Gasparrini, Antonio; Armstrong, Ben G; Tawatsupa, Benjawan; Tobias, Aurelio; Lavigne, Eric; Coelho, Micheline de Sousa Zanotti Stagliorio; Pan, Xiaochuan; Kim, Ho; Hashizume, Masahiro; Honda, Yasushi; Guo, Yue-Liang Leon; Wu, Chang-Fu; Zanobetti, Antonella; Schwartz, Joel D; Bell, Michelle L; Scortichini, Matteo; Michelozzi, Paola; Punnasiri, Kornwipa; Li, Shanshan; Tian, Linwei; Garcia, Samuel David Osorio; Seposo, Xerxes; Overcenco, Ala; Zeka, Ariana; Goodman, Patrick; Dang, Tran Ngoc; Dung, Do Van; Mayvaneh, Fatemeh; Saldiva, Paulo Hilario Nascimento; Williams, Gail; Tong, Shilu

    2017-08-10

    Few studies have examined variation in the associations between heat waves and mortality in an international context. We aimed to systematically examine the impacts of heat waves on mortality with lag effects internationally. We collected daily data of temperature and mortality from 400 communities in 18 countries/regions and defined 12 types of heat waves by combining community-specific daily mean temperature ≥90th, 92.5th, 95th, and 97.5th percentiles of temperature with duration ≥2, 3, and 4 d. We used time-series analyses to estimate the community-specific heat wave-mortality relation over lags of 0-10 d. Then, we applied meta-analysis to pool heat wave effects at the country level for cumulative and lag effects for each type of heat wave definition. Heat waves of all definitions had significant cumulative associations with mortality in all countries, but varied by community. The higher the temperature threshold used to define heat waves, the higher heat wave associations on mortality. However, heat wave duration did not modify the impacts. The association between heat waves and mortality appeared acutely and lasted for 3 and 4 d. Heat waves had higher associations with mortality in moderate cold and moderate hot areas than cold and hot areas. There were no added effects of heat waves on mortality in all countries/regions, except for Brazil, Moldova, and Taiwan. Heat waves defined by daily mean and maximum temperatures produced similar heat wave-mortality associations, but not daily minimum temperature. Results indicate that high temperatures create a substantial health burden, and effects of high temperatures over consecutive days are similar to what would be experienced if high temperature days occurred independently. People living in moderate cold and moderate hot areas are more sensitive to heat waves than those living in cold and hot areas. Daily mean and maximum temperatures had similar ability to define heat waves rather than minimum temperature

  15. Responses of tree species to heat waves and extreme heat events

    National Research Council Canada - National Science Library

    TESKEY, ROBERT; WERTIN, TIMOTHY; BAUWERAERTS, INGVAR; AMEYE, MAARTEN; MCGUIRE, MARY ANNE; STEPPE, KATHY

    2015-01-01

    .... At the whole plant level, heat stress can decrease growth and shift biomass allocation. When drought stress accompanies heat waves, the negative effects of heat stress are exacerbated and can lead to tree mortality...

  16. Heat Sponge: A Concept for Mass-Efficient Heat Storage

    Science.gov (United States)

    Splinter, Scott C.; Blosser, Max L.; Gifford, Andrew R.

    2008-01-01

    The heat sponge is a device for mass-efficient storage of heat. It was developed to be incorporated in the substructure of a re-entry vehicle to reduce thermal- protection-system requirements. The heat sponge consists of a liquid/vapor mixture contained within a number of miniature pressure vessels that can be embedded within a variety of different types of structures. As temperature is increased, pressure in the miniature pressure vessels also increases so that heat absorbed through vaporization of the liquid is spread over a relatively large temperature range. Using water as a working fluid, the heat-storage capacity of the liquid/vapor mixture is many times higher than that of typical structural materials and is well above that of common phase change materials over a temperature range of 200 F to 700 F. The use of pure ammonia as the working fluid provides a range of application between 432 deg R and 730 deg R, or the use of the more practical water-ammonia solution provides a range of application between 432 deg R and 1160 deg R or in between that of water and pure ammonia. Prototype heat sponges were fabricated and characterized. These heat sponges consisted of 1.0-inch-diameter, hollow, stainless-steel spheres with a wall thickness of 0.020 inches which had varying percentages of their interior volumes filled with water and a water-ammonia solution. An apparatus to measure the heat stored in these prototype heat sponges was designed, fabricated, and verified. The heat-storage capacity calculated from measured temperature histories is compared to numerical predictions.

  17. The research of heating efficiency of different induction heating systems

    Directory of Open Access Journals (Sweden)

    Konesev Sergey

    2017-01-01

    Full Text Available Computer models of tape and coil inductors are described, and a comparison of the heating efficiency depending on various parameters is made. The developed computer model was made in the ELCUT 6.0. As a result of the simulation, data on the heating characteristics (depending on the various parameters of the heating elements are obtained. The average statistical data of a series of experiments with a tape inductor are given. It is shown that for the same parameters (values of inductance and number of wires, the tape version inductor heats up a pipe to a higher temperature (by 5.08% than the inductor in the coil version in 10 minutes.

  18. Impact of Heat Wave Definitions on the Added Effect of Heat Waves on Cardiovascular Mortality in Beijing, China

    Directory of Open Access Journals (Sweden)

    Wentan Dong

    2016-09-01

    Full Text Available Heat waves are associated with increased mortality, however, few studies have examined the added effect of heat waves. Moreover, there is limited evidence for the influence of different heat wave definitions (HWs on cardiovascular mortality in Beijing, the capital of China. The aim of this study was to find the best HW definitions for cardiovascular mortality, and we examined the effect modification by an individual characteristic on cardiovascular mortality in Beijing, a typical northern city in China. We applied a Poisson generalized additive approach to estimate the differences in cardiovascular mortality during heat waves (using 12 HWs compared with non-heat-wave days in Beijing from 2006 to 2009. We also validated the model fit by checking the residuals to ensure that the autocorrelation was successfully removed. In addition, the effect modifications by individual characteristics were explored in different HWs. Our results showed that the associations between heat waves and cardiovascular mortality differed from different HWs. HWs using the 93th percentile of the daily average temperature (27.7 °C and a duration ≥5 days had the greatest risk, with an increase of 18% (95% confidence interval (CI: 6%, 31% in the overall population, 24% (95% CI: 10%, 39% in an older group (ages ≥65 years, and 22% (95% CI: 3%, 44% in a female group. The added effect of heat waves was apparent after 5 consecutive heat wave days for the overall population and the older group. Females and the elderly were at higher risk than males and younger subjects (ages <65 years. Our findings suggest that heat wave definitions play a significant role in the relationship between heat wave and cardiovascular mortality. Using a suitable definition may have implications for designing local heat early warning systems and protecting the susceptible populations during heat waves.

  19. Improving efficiency of heat recovery steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Ganapathy, V. [ABCO Industries, Abilene, TX (United States)

    1996-10-01

    Gas Turbine Heat Recovery Steam Generators (HRSGs) are widely used in cogeneration and combined cycle plants. Single pressure HRSGs are preferred in small capacity units, while larger units can justify multiple pressure level steam generation, which improves the efficiency of energy recovery. This paper reviews a few methods of improving the efficiency of single and multiple pressure HRSGs, which may be of interest to consultants and plant engineers, who are planning new cogeneration projects.

  20. Changes of heat waves characteristics over the territory of Slovakia

    Science.gov (United States)

    Kollarikova, Patricia; Szolgay, Jan; Pecho, Jozef

    2014-05-01

    The study is focused on the analysis of long-term changes and trends of heat waves occurrence in selected meteorological stations in Slovakia. Changes of the temperature regime of the hydro-climatic system may have serious consequences on population health. It is expected that climate change could, in the next decades, also lead to a higher frequency and greater spatial extent of extreme heat waves in Central Europe. Heat waves can cause severe thermal environmental stress, health complications, higher hospital admission rates, and increased mortality. A larger number of consecutive warm days and nights can also lead to increased solar overheating of buildings, inhibited ventilation, etc. Detection of possible ongoing changes of the regime of heat ways is therefore of particular interest. Since heat waves can be quantitatively evaluated through their temperature range (extremity) and also according to their duration, a set of such characteristics using statistical methods were analysed using maximum and average daily air temperature time series from the 1951-2010 period in 8 meteorological stations over the territory of Slovakia. Results indicate an overall consistent (both in time and space) increase of selected heat wave characteristics in Slovakia mostly due to their occurrence in the last two decades (1991 to 2010). This period was characterised by the occurrence of the most extreme heat waves ever recorded in history of meteorological observations in Slovakia (years 1992, 1994, 1998, 2003, 2007, 2010). The absolutely longest and most extreme heat wave occurred in southern Slovakia (station Hurbanovo) in 1992, when one heat wave lasted 47 days, while the cumulative amount of the deviation from 30 °C reached over 106 ° C. Change of the heat waves character in the last two decades was also indicated. Compared with the previous decade (1991-2000), during the decade of 2001-2010, the heat waves had shorter durations, but their total extremity and the quantity

  1. Wave Heating of the Solar Chromosphere Wolfgang Kalkofen

    Indian Academy of Sciences (India)

    chromosphere is heated mainly by waves related to the magnetic field. If that were correct, the whole chromosphere, magnetic as well as nonmag- netic, would be heated mainly by waves related to the magnetic field. But contrary to expectation, the radiation emerging from the nonmagnetic chro- mosphere shows none of ...

  2. Heat Wave Changes in the Eastern Mediterranean since 1960

    Science.gov (United States)

    Kuglitsch, Franz G.; Toreti, Andrea; Xoplaki, Elena; Della-Marta, Paul M.; Zerefos, Christos S.; Türkes, Murat; Luterbacher, Jürg

    2010-05-01

    Heat waves have discernible impacts on mortality and morbidity, infrastructure, agricultural resources, the retail industry, ecosystem and tourism and consequently affect human societies. A new definition of socially relevant heat waves is presented and applied to new data sets of high-quality homogenized daily maximum and minimum summer air temperature series from 246 stations in the eastern Mediterranean region (including Albania, Bosnia-Herzegovina, Bulgaria, Croatia, Cyprus, Greece, Israel, Romania, Serbia, Slovenia, Turkey). Changes in heat wave number, length and intensity between 1960 and 2006 are quantified. Daily temperature homogeneity analysis suggest that many instrumental measurements in the 1960s are warm-biased, correcting for these biases regionally averaged heat wave trends are up to 8% higher. We find significant changes across the western Balkans, southwestern and western Turkey, and along the southern Black Sea coastline. Since the 1960s, the mean heat wave intensity, heat wave length and heat wave number across the eastern Mediterranean region have increased by a factor 7.6 ±1.3, 7.5 ±1.3 and 6.2 ±1.1, respectively. These findings suggest that the heat wave increase in this region is higher than previously reported.

  3. Quantifying impacts of heat waves on power grid operation

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Xinda; Wu, Di; Rice, Jennie S.; Kintner-Meyer, Michael CW; Lu, Ning

    2016-12-01

    Climate change is projected to cause an increase in the severity and frequency of extreme weather events such as heat waves and droughts. Such changes present planning and operating challenges and risks to many economic sectors. In the electricity sector, statistics of extreme events in the past have been used to help plan for future peak loads, determine associated infrastructure requirements, and evaluate operational risks, but industry-standard planning tools have yet to be coupled with or informed by temperature models to explore the impacts of the "new normal" on planning studies. For example, high ambient temperatures during heat waves reduce the output capacity and efficiency of gas fired combustion turbines just when they are needed most to meet peak demands. This paper describes the development and application of a production cost and unit commitment model coupled to high resolution, hourly temperature data and a temperature dependent load model. The coupled system has the ability to represent the impacts of hourly temperatures on load conditions and available capacity and efficiency of combustion turbines, and therefore capture the potential impacts on system reliability and production cost. Ongoing work expands this capability to address the impacts of water availability and temperature on power grid operation.

  4. Modeling of ICRF wave propagation and heating in EAST with the full-wave code TORIC

    Science.gov (United States)

    Edlund, E. M.; Bonoli, P. T.; Porkolab, M.; Wukitch, S. J.

    2015-11-01

    Access to advanced tokamak (AT) scenarios in EAST depends on efficient coupling of the launched ion-cyclotron range of frequency (ICRF) power for heating and lower-hybrid waves to the plasma for steady-state current drive. This work builds on recent predictions from the full-wave code TORIC that have shown significant reductions in loading, resulting in improved heating efficiency, by operating with smaller phasing between antenna straps. The density regime of typical EAST experiments produces perpendicular wavelengths of the fast-wave that are comparable to the minor radius of the plasma, resulting in cavity-resonance effects and requiring full-spectrum analysis for accurate calculations of the antenna coupling. This study examines the effects of antenna phasing, as well as plasma density, temperature and current as control parameters for achieving good coupling of the ICRF power in the pursuit of the optimal conditions for AT plasmas. This work is funded by the US DOE under contract DoE Grant DE-SC0010492.

  5. Measurement of heat and moisture exchanger efficiency.

    Science.gov (United States)

    Chandler, M

    2013-09-01

    Deciding between a passive heat and moisture exchanger or active humidification depends upon the level of humidification that either will deliver. Published international standards dictate that active humidifiers should deliver a minimum humidity of 33 mg.l(-1); however, no such requirement exists, for heat and moisture exchangers. Anaesthetists instead have to rely on information provided by manufacturers, which may not allow comparison of different devices and their clinical effectiveness. I suggest that measurement of humidification efficiency, being the percentage moisture returned and determined by measuring the temperature of the respired gases, should be mandated, and report a modification of the standard method that will allow this to be easily measured. In this study, different types of heat and moisture exchangers for adults, children and patients with a tracheostomy were tested. Adult and paediatric models lost between 6.5 mg.l(-1) and 8.5 mg.l(-1) moisture (corresponding to an efficiency of around 80%); however, the models designed for patients with a tracheostomy lost between 16 mg.l(-1) and 18 mg.l(-1) (60% efficiency). I propose that all heat and moisture exchangers should be tested in this manner and percentage efficiency reported to allow an informed choice between different types and models. © 2013 The Association of Anaesthetists of Great Britain and Ireland.

  6. Heat waves and urban heat islands in Europe: A review of relevant drivers.

    Science.gov (United States)

    Ward, Kathrin; Lauf, Steffen; Kleinschmit, Birgit; Endlicher, Wilfried

    2016-11-01

    The climate change and the proceeding urbanization create future health challenges. Consequently, more people around the globe will be impaired by extreme weather events, such as heat waves. This study investigates the causes for the emergence of surface urban heat islands and its change during heat waves in 70 European cities. A newly created climate class indicator, a set of meaningful landscape metrics, and two population-related parameters were applied to describe the Surface Urban Heat Island Magnitude (SUHIM) - the mean temperature increase within the urban heat island compared to its surrounding, as well as the Heat Magnitude (HM) - the extra heat load added to the average summer SUHIM during heat waves. We evaluated the relevance of varying urban parameters within linear models. The exemplary European-wide heat wave in July 2006 was chosen and compared to the average summer conditions using MODIS land surface temperature with an improved spatial resolution of 250m. The results revealed that the initial size of the urban heat island had significant influence on SUHIM. For the explanation of HM the size of the heat island, the regional climate and the share of central urban green spaces showed to be critical. Interestingly, cities of cooler climates and cities with higher shares of urban green spaces were more affected by additional heat during heat waves. Accordingly, cooler northern European cities seem to be more vulnerable to heat waves, whereas southern European cities appear to be better adapted. Within the ascertained population and climate clusters more detailed explanations were found. Our findings improve the understanding of the urban heat island effect across European cities and its behavior under heat waves. Also, they provide some indications for urban planners on case-specific adaptation strategies to adverse urban heat caused by heat waves. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Traveling-Wave Tube Efficiency Enhancement

    Science.gov (United States)

    Dayton, James A., Jr.

    2011-01-01

    Traveling-wave tubes (TWT's) are used to amplify microwave communication signals on virtually all NASA and commercial spacecraft. Because TWT's are a primary power user, increasing their power efficiency is important for reducing spacecraft weight and cost. NASA Glenn Research Center has played a major role in increasing TWT efficiency over the last thirty years. In particular, two types of efficiency optimization algorithms have been developed for coupled-cavity TWT's. The first is the phase-adjusted taper which was used to increase the RF power from 420 to 1000 watts and the RF efficiency from 9.6% to 22.6% for a Ka-band (29.5 GHz) TWT. This was a record efficiency at this frequency level. The second is an optimization algorithm based on simulated annealing. This improved algorithm is more general and can be used to optimize efficiency over a frequency bandwidth and to provide a robust design for very high frequency TWT's in which dimensional tolerance variations are significant.

  8. Human-biometeorological assessment of heat waves in Athens

    Science.gov (United States)

    Matzarakis, Andreas; Nastos, Panagiotis T.

    2011-08-01

    The goal of this study is the analysis of heat waves and their impact on humans, using human biometeorological indices, which are based on the energy balance of the human body. The implications for humans are not only described through the intensity of the heat waves, but also through their duration over consecutive days. Both intensity and duration were analyzed for the Greater Athens Area during the period 1955 to 2001. The analysis was carried out using the daily physiologically equivalent temperature and the daily minimum air temperature. Based on these two parameters, the results showed an increase in the average duration of heat waves. Furthermore, the use of the Gaussian filter revealed the intra-annual variation of heat stress conditions and their relevance to humans. The results could be used for the management of the negative consequences of heat waves in cities suffering from environmental pollution and also for climate impact studies.

  9. Thermodynamic Efficiency of Pumped Heat Electricity Storage

    Science.gov (United States)

    Thess, André

    2013-09-01

    Pumped heat electricity storage (PHES) has been recently suggested as a potential solution to the large-scale energy storage problem. PHES requires neither underground caverns as compressed air energy storage (CAES) nor kilometer-sized water reservoirs like pumped hydrostorage and can therefore be constructed anywhere in the world. However, since no large PHES system exists yet, and theoretical predictions are scarce, the efficiency of such systems is unknown. Here we formulate a simple thermodynamic model that predicts the efficiency of PHES as a function of the temperature of the thermal energy storage at maximum output power. The resulting equation is free of adjustable parameters and nearly as simple as the well-known Carnot formula. Our theory predicts that for storage temperatures above 400°C PHES has a higher efficiency than existing CAES and that PHES can even compete with the efficiencies predicted for advanced-adiabatic CAES.

  10. ASSESSING HUMAN CONTRIBUTION TO THE SUMMER 2013 KOREAN HEAT WAVE

    National Research Council Canada - National Science Library

    Seung-Ki Min; Yeon-Hee Kim; Maeng-Ki Kim; Changyong Park

    2014-01-01

      Here, we assess the Korean heat wave in the context of global warming using recent climate model datasets available from the Coupled Model Intercomparison Project Phase 5 (CMIP5; Taylor et al. 2012) experiments...

  11. Event Attribution of the August 2010 Russian Heat Wave

    National Research Council Canada - National Science Library

    Watanabe, Masahiro; Shiogama, Hideo; Imada, Yukiko; Mori, Masato; Ishii, Masayoshi; Kimoto, Masahide

    2013-01-01

    An extreme heat wave hit western Russia in the summer of 2010. To investigate the contribution of anthropogenic climate change to this event, 100-member ensembles of atmospheric general circulation model (AGCM...

  12. Synoptic Conditions Generating Heat Waves and Warm Spells in Romania

    Directory of Open Access Journals (Sweden)

    Lucian Sfîcă

    2017-03-01

    Full Text Available Heat waves and warm spells are extreme meteorological events that generate a significant number of casualties in temperate regions, as well as outside of temperate regions. For the purpose of this paper, heat waves and warm spells were identified based on daily maximum temperatures recorded at 27 weather stations located in Romania over a 55-year period (1961–2015. The intensity threshold was the 90th percentile, and the length of an event was of minimum three consecutive days. We analyzed 111 heat wave and warm spell events totaling 423 days. The classification of synoptic conditions was based on daily reanalysis at three geopotential levels and on the online version of a backward trajectories model. The main findings are that there are two major types of genetic conditions. These were identified as: (i radiative heat waves and warm spells (type A generated by warming the air mass due to high amounts of radiation which was found dominant in warm season; and (ii advective heat waves and warm spells (type B generated mainly by warm air mass advection which prevails in winter and transition seasons. These major types consist of two and three sub-types, respectively. The results could become a useful tool for weather forecasters in order to better predict the occurrence of heat waves and warm spells.

  13. An analysis of heat wave trends using heat index in East Malaysia

    Science.gov (United States)

    Suparta, W.; Yatim, A. N. M.

    2017-05-01

    This paper aimed to investigate the heat wave trends in East Malaysia based on the National Weather Services (NWS) Heat Index. The heat index was calculated by using mean temperature and mean relative humidity on monthly basis for 5 meteorological stations in East Malaysia during the period 2008 to 2010. The trends for heat wave were estimated from Heat Index based on the least square regression analysis at each station level. Results showed that the heat wave trends are increasing at all stations. The highest heat index was occurred in Sandakan on July 2010 with heat index 35°C while the lowest heat index happened at Kuching in January 2009 with 27.3°C. From the heat wave observed, East Malaysia is still in caution categories or normal condition (27°C-32°C) and the extreme caution (32°C-41°C) was observed during southwest monsoon (May-July). The safety condition of heat waves in East Malaysia is possibly due to weak to moderate El Nino occurred during the period of observation.

  14. Efficient Rasterization for Outdoor Radio Wave Propagation.

    Science.gov (United States)

    Schmitz, A; Rick, T; Karolski, T; Kuhlen, T; Kobbelt, L

    2011-02-01

    Conventional beam tracing can be used for solving global illumination problems. It is an efficient algorithm and performs very well when implemented on the GPU. This allows us to apply the algorithm in a novel way to the problem of radio wave propagation. The simulation of radio waves is conceptually analogous to the problem of light transport. We use a custom, parallel rasterization pipeline for creation and evaluation of the beams. We implement a subset of a standard 3D rasterization pipeline entirely on the GPU, supporting 2D and 3D frame buffers for output. Our algorithm can provide a detailed description of complex radio channel characteristics like propagation losses and the spread of arriving signals over time (delay spread). Those are essential for the planning of communication systems required by mobile network operators. For validation, we compare our simulation results with measurements from a real-world network. Furthermore, we account for characteristics of different propagation environments and estimate the influence of unknown components like traffic or vegetation by adapting model parameters to measurements.

  15. Bulk Ion Heating with ICRF Waves in Tokamaks

    DEFF Research Database (Denmark)

    Mantsinen, M. J.; Bilato, R.; Bobkov, V. V.

    2015-01-01

    Heating with ICRF waves is a well-established method on present-day tokamaks and one of the heating systems foreseen for ITER. However, further work is still needed to test and optimize its performance in fusion devices with metallic high-Z plasma facing components (PFCs) in preparation of ITER a...

  16. Heat conversion alternative petrochemical complexes efficiency

    Science.gov (United States)

    Mrakin, A. N.; Selivanov, A. A.; Morev, A. A.; Batrakov, P. A.; Kulbyakina, A. V.; Sotnikov, D. G.

    2017-08-01

    The paper presents the energy and economic efficiency calculation results of the petrochemical complexes based upon the sulfur oil shales processing by solid (ash) heat-carrier low-temperature carbonization plants by Galoter technology. The criterion for such enterprises fuel efficiency determining was developed on the base of the exergy methodology taking into account the recurrent publications consolidation. In this case, in supplying the consumers with paving bitumen, motor benzol, thiophene, toluene, 2-methylthiophene, xylene, gas sulfur, complex thermodynamic effectiveness was founded to amount to 53 %, and if ash residue realization is possible then it was founded to be to 70 %. The project economic attractiveness determining studies depending on the feedstock cost, its delivery way and investments amount changing were conducted.

  17. Energy efficient heating and ventilation of large halls

    CERN Document Server

    Hojer, Ondrej; Kabele, Karel; Kotrbaty, Miroslav; Sommer, Klaus; Petras, Dusan

    2011-01-01

    This guidebook is focused on modern methods for design, control and operation of energy efficient heating systems in large spaces and industrial halls. The book deals with thermal comfort, light and dark gas radiant heaters, panel radiant heating, floor heating and industrial air heating systems. Various heating systems are illustrated with case studies. Design principles, methods and modeling tools are presented for various systems.

  18. Syndromic surveillance and heat wave morbidity: a pilot study based on emergency departments in France.

    Science.gov (United States)

    Josseran, Loïc; Caillère, Nadège; Brun-Ney, Dominique; Rottner, Jean; Filleul, Laurent; Brucker, Gilles; Astagneau, Pascal

    2009-02-20

    The health impacts of heat waves are serious and have prompted the development of heat wave response plans. Even when they are efficient, these plans are developed to limit the health effects of heat waves. This study was designed to determine relevant indicators related to health effects of heat waves and to evaluate the ability of a syndromic surveillance system to monitor variations in the activity of emergency departments over time. The study uses data collected during the summer 2006 when a new heat wave occurred in France. Data recorded from 49 emergency departments since July 2004, were transmitted daily via the Internet to the French Institute for Public Health Surveillance. Items collected on patients included diagnosis (ICD10 codes), outcome, and age. Statistical t-tests were used to compare, for several health conditions, the daily averages of patients within different age groups and periods (whether 'on alert' or 'off alert'). A limited number of adverse health conditions occurred more frequently during hot period: dehydration, hyperthermia, malaise, hyponatremia, renal colic, and renal failure. Over all health conditions, the total number of patients per day remained equal between the 'on alert' and 'off alert' periods (4,557.7/day vs. 4,511.2/day), but the number of elderly patients increased significantly during the 'on alert' period relative to the 'off alert' period (476.7/day vs. 446.2/day p waves.

  19. An "H-index" for summer heat waves

    Science.gov (United States)

    Teuling, Ryan; Vautard, Robert

    2013-04-01

    Heat waves are among the most severely impacting natural disasters with which we contend. Recent summer "mega-heatwave" extremes in France (2003) and Russia (2010) lead to impacts on ecosystems and economic sectors, as well as increased mortality rates. Appropriate adaptation measures and improved early warning systems are necessary to cope with more frequent phenomena such as those that occurred in the last decade. A simple scale, that allows both identification, definition and ranking of individual heat wave events based on environmental conditions and potential for societal impact, is lacking. Such magnitude scale could also help to evaluate the evolution of heat waves in multi-model climate projections as compared to current climate. A simple index, easy to calculate and communicate, is designed to capture both the intensity and duration of summer heat waves. The index, analogous to the Hirsch index for citations, expresses the magnitude of a heat wave event (H) by the number of subsequent days H over which the daily average apparent temperature anomaly exceeds H K. It accounts for the magnitude of the day- and night-time temperature anomalies, humidity and wind, as well as for the duration of the heat wave episode. As a preliminary application, we calculated H over a 36 year-long global set of meteorological station data, after a careful quality check procedure. We show that these events, as characterised by H, have doubled in number over the past few decades. We also show that large magnitude heat waves (say H≥8) occur essentially in mid to high latitudes and over continental areas.

  20. Social media responses to heat waves

    Science.gov (United States)

    Jung, Jihoon; Uejio, Christopher K.

    2017-07-01

    Social network services (SNSs) may benefit public health by augmenting surveillance and distributing information to the public. In this study, we collected Twitter data focusing on six different heat-related themes (air conditioning, cooling center, dehydration, electrical outage, energy assistance, and heat) for 182 days from May 7 to November 3, 2014. First, exploratory linear regression associated outdoor heat exposure to the theme-specific tweet counts for five study cities (Los Angeles, New York, Chicago, Houston, and Atlanta). Next, autoregressive integrated moving average (ARIMA) time series models formally associated heat exposure to the combined count of heat and air conditioning tweets while controlling for temporal autocorrelation. Finally, we examined the spatial and temporal distribution of energy assistance and cooling center tweets. The result indicates that the number of tweets in most themes exhibited a significant positive relationship with maximum temperature. The ARIMA model results suggest that each city shows a slightly different relationship between heat exposure and the tweet count. A one-degree change in the temperature correspondingly increased the Box-Cox transformed tweets by 0.09 for Atlanta, 0.07 for Los Angeles, and 0.01 for New York City. The energy assistance and cooling center theme tweets suggest that only a few municipalities used Twitter for public service announcements. The timing of the energy assistance tweets suggests that most jurisdictions provide heating instead of cooling energy assistance.

  1. Study of heat-stress levels in naturally ventilated sheep barns during heat waves: development and assessment of regression models

    Science.gov (United States)

    Papanastasiou, D. K.; Bartzanas, T.; Panagakis, P.; Zhang, G.; Kittas, C.

    2016-11-01

    It is well documented that heat-stress burdens sheep welfare and productivity. Peak heat-stress levels are observed when high temperatures prevail, i.e. during heat waves; however, continuous measurements inside livestock buildings are not usually available for long periods so as to study the variation of summer heat-stress levels for several years, especially during extreme hot weather. Α methodology to develop a long time series of summer temperature and relative humidity inside naturally ventilated sheep barns is proposed. The accuracy and the transferability of the developed linear regression models were verified. Temperature Humidity Index (THI) was used to assess sheep's potential heat-stress. Τhe variation of THI inside a barn during heat wave and non-heat wave days was examined, and the results were comparatively assessed. The analysis showed that sheep were exposed to moderate, severe, and extreme severe heat-stress in 10, 21 and 66 % of hours, respectively, during heat wave days, while the corresponding values during non-heat wave days were 14, 33 and 43 %, respectively. The heat load on sheep was much higher during heat wave events than during non-heat wave periods. Additionally, based on the averaged diurnal variation of THI, it was concluded that extreme severe heat-stress conditions were prevailing between 1000 and 2400 hours local time during heat wave days. Cool off night periods were never and extremely rarely detected during heat wave and non-heat wave days, respectively.

  2. Public crowdsensing of heat waves by social media data

    Science.gov (United States)

    Grasso, Valentina; Crisci, Alfonso; Morabito, Marco; Nesi, Paolo; Pantaleo, Gianni

    2017-07-01

    Investigating on society-related heat wave hazards is a global issue concerning the people health. In the last two decades, Europe experienced several severe heat wave episodes with catastrophic effects in term of human mortality (2003, 2010 and 2015). Recent climate investigations confirm that this threat will represent a key issue for the resiliency of urban communities in next decades. Several important mitigation actions (Heat-Health Action Plans) against heat hazards have been already implemented in some WHO (World Health Organization) European region member states to encourage preparedness and response to extreme heat events. Nowadays, social media (SM) offer new opportunities to indirectly measure the impact of heat waves on society. Using the crowdsensing concept, a micro-blogging platform like Twitter may be used as a distributed network of mobile sensors that react to external events by exchanging messages (tweets). This work presents a preliminary analysis of tweets related to heat waves that occurred in Italy in summer 2015. Using TwitterVigilance dashboard, developed by the University of Florence, a sample of tweets related to heat conditions was retrieved, stored and analyzed for main features. Significant associations between the daily increase in tweets and extreme temperatures were presented. The daily volume of Twitter users and messages revealed to be a valuable indicator of heat wave impact at the local level, in urban areas. Furthermore, with the help of Generalized Additive Model (GAM), the volume of tweets in certain locations has been used to estimate thresholds of local discomfort conditions. These city-specific thresholds are the result of dissimilar climatic conditions and risk cultures.

  3. Public crowdsensing of heat waves by social media data

    Directory of Open Access Journals (Sweden)

    V. Grasso

    2017-07-01

    Full Text Available Investigating on society-related heat wave hazards is a global issue concerning the people health. In the last two decades, Europe experienced several severe heat wave episodes with catastrophic effects in term of human mortality (2003, 2010 and 2015. Recent climate investigations confirm that this threat will represent a key issue for the resiliency of urban communities in next decades. Several important mitigation actions (Heat-Health Action Plans against heat hazards have been already implemented in some WHO (World Health Organization European region member states to encourage preparedness and response to extreme heat events. Nowadays, social media (SM offer new opportunities to indirectly measure the impact of heat waves on society. Using the crowdsensing concept, a micro-blogging platform like Twitter may be used as a distributed network of mobile sensors that react to external events by exchanging messages (tweets. This work presents a preliminary analysis of tweets related to heat waves that occurred in Italy in summer 2015. Using TwitterVigilance dashboard, developed by the University of Florence, a sample of tweets related to heat conditions was retrieved, stored and analyzed for main features. Significant associations between the daily increase in tweets and extreme temperatures were presented. The daily volume of Twitter users and messages revealed to be a valuable indicator of heat wave impact at the local level, in urban areas. Furthermore, with the help of Generalized Additive Model (GAM, the volume of tweets in certain locations has been used to estimate thresholds of local discomfort conditions. These city-specific thresholds are the result of dissimilar climatic conditions and risk cultures.

  4. Heating of solar coronal loops by resonant absorption of Alfven waves

    Science.gov (United States)

    Grossmann, William; Smith, Robert A.

    1988-01-01

    Numerical calculations governing the efficiency of coronal loop heating by the resonant absorption of shear Alfven waves are reported. The loop structure is modeled by a class of axisymmetric force-free equilibria of a long straight cylinder, approximating a large aspect ratio loop. For a range of parameters characterizing the evolution of solar coronal loops, the absorption bandwidth falls in the frequency range of the photospheric motions due to granulation and p-modes. Resonant Alfven wave absorption is thus a viable mechanism for coronal loop heating.

  5. Energy Efficient Clothes Dryer with IR Heating and Electrostatic Precipitator

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Stanton [GE Global Research, Niskayuna, NY (United States)

    2017-12-12

    The project goal was to develop a revolutionary energy saving technology for residential clothes drying. The team developed an IR (infrared) heating system and NESP (Nebulizer and Electro-Static Precipitator) for integration into a ventless clothes dryer. The proposed technology addresses two of the major inefficiencies in current electric vented dryers by providing effective energy transfer for the removal of the water and recapture of the vapor latent heat. The IR heaters operating in the mid wave (2.5-10um) are very efficient as they target the 3-micron peak absorption of the water molecule. This allows direct energy absorption, unlike conventional element heaters where heat is transferred by convection. The low power NESP removes water vapor from the exhausted stream and recaptures the latent heat in the ESP (Electro-Static Precipitator) exchanger section. This allows the warm dry air to be recirculated back into the drum for additional efficiency savings. The remaining majority of the dryer hardware stays the same. Summing the efficiency gain from the two subcomponents we anticipated the EF (Efficiency Factor) to exceed the goal of 4.04. EF is obtained by dividing the weight (lbs) of water removed by the energy (kWhr) used, where the test load size is 8.45 lbs of bone dry clothing wetted to 57.5% or 4.8lbs of water, and dried to a remaining moisture content of 2.5-5%. Additional benefits include not having to recondition (heat or cool) the large amounts of make-up air to replace the air exhausted by a vented dryer. It was anticipated that the NESP/heat exchanger would be the most challenging and highest risk element in the program. Therefore, the team focused their efforts during Phase 1 of the program on the design, construction, testing, and optimization of the NESP/heat exchanger. At the end Phase 1, the team compared the performance of the NESP/heat exchanger with the system level requirements and made a Go/No-Go decision on proceeding with the second

  6. Evidence for wave heating in the solar corona.

    Science.gov (United States)

    Hahn, Michael

    2013-07-01

    The temperature of the Sun increases over a short distance from a few thousand degrees in the photosphere to over a million degrees in the corona. To understand coronal heating is one of the major problems in astrophysics. There is general agreement that the energy source is convective motion in and below the photosphere. It remains to determine how this mechanical energy is transported outward into the corona and then deposited as heat. Two classes of models have been proposed, namely those that rely on magnetic reconnection and those that rely on waves, particularly Alfvén waves. There is increasing evidence that waves are ubiquitous in the corona. However, a difficulty for wave-driven models has been that most theories predict Alfvén waves to be undamped in the corona, and therefore they cannot dissipate their energy into heat. Our research has shown unambiguous observational evidence that the waves do damp at sufficiently low heights in the corona to be important for coronal heating. © 2013 New York Academy of Sciences.

  7. Field Measurements of Heating System Efficiency in Nine Electrically-Heated Manufactured Homes.

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Bob; Siegel, J.; Palmiter, L.; Baylon, D.

    1996-07-01

    This report presents the results of field measurements of heating efficiency performed on nine manufactured homes sited in the Pacific Northwest. The testing procedure collects real-time data on heating system energy use and heating zone temperatures, allowing direct calculation of heating system efficiency.

  8. Increasing the Efficiency of Maple Sap Evaporators with Heat Exchangers

    Science.gov (United States)

    Lawrence D. Garrett; Howard Duchacek; Mariafranca Morselli; Frederick M. Laing; Neil K. Huyler; James W. Marvin

    1977-01-01

    A study of the engineering and economic effects of heat exchangers in conventional maple syrup evaporators indicated that: (1) Efficiency was increased by 15 to 17 percent with heat exchangers; (2) Syrup produced in evaporators with heat exchangers was similar to syrup produced in conventional systems in flavor and in chemical and physical composition; and (3) Heat...

  9. Loop heat pipes - highly efficient heat-transfer devices for systems of sun heat supply

    Energy Technology Data Exchange (ETDEWEB)

    Maydanik, Yu. [Ural Branch of the Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of Thermophysics

    2004-07-01

    Loop heat pipes (LHPs) are hermetic heat-transfer devices operating on a closed evaporation-condensation cycle with the use of capillary pressure for pumping the working fluid [1]. In accordance with this, they possess all the main advantages of conventional heat pipes, but, as distinct from the latter, have a considerably higher heat-transfer capacity, especially when operating in the ''antigravity'' regime, when heat is transferred from above downwards. Besides, LHPs possess a higher functional versatility, are adaptable to different operating conditions and provide great scope for various design embodiments. This is achieved at the expense of both the original design of the device and the properties of the wick - a special capillary structure used for the creation of capillary pressure. The LHP schematic diagram is given in Fig. 1. The device contains an evaporator and a condenser - heat exchanger connected by means of smooth-walled pipe-lines with a relatively small diameter intended for separate motion of vapor and liquid. At present loop heat pipes are most extensively employed in thermoregulation systems of spacecrafts. Miniature LHPs are used for cooling electronics and computers. At the same time there exists a considerable potential of using these devices for the recovery of low-grade (waste) heat from different sources, and also in systems of sun heat supply. In the latter case LHPs may serve as an efficient heat-transfer link between a sun collector and a heat accumulator, which has a low thermal resistance and does not consume any additional energy for pumping the working fluid between them. (orig.)

  10. District heating biofuel burner efficiency and energy balance

    OpenAIRE

    Okoro, Oluwashola Aderemi

    2015-01-01

    District heating is an optimal system of distributing heat to residential building in a centralized location through pipeline networks. The district heating of woodchip is cost effective, improve energy efficiency, reduce gas emissions and improve energy security. The thermal efficiency and energy balance in a boiler is obtained by combustion analysis of the wood (fuel). In this report, the district heating bio fuel burner in Skien Fjernvarme is considered. The capacity of the boiler is 6MW a...

  11. Cutting efficiency of Reciproc and waveOne reciprocating instruments.

    Science.gov (United States)

    Plotino, Gianluca; Giansiracusa Rubini, Alessio; Grande, Nicola M; Testarelli, Luca; Gambarini, Gianluca

    2014-08-01

    The aim of the present study was to evaluate the cutting efficiency of 2 new reciprocating instruments, Reciproc and WaveOne. Twenty-four new Reciproc R25 and 24 new WaveOne Primary files were activated by using a torque-controlled motor (Silver Reciproc) and divided into 4 groups (n = 12): group 1, Reciproc activated by Reciproc ALL program; group 2, Reciproc activated by WaveOne ALL program; group 3, WaveOne activated by Reciproc ALL program; and group 4, WaveOne activated by WaveOne ALL program. The device used for the cutting test consisted of a main frame to which a mobile plastic support for the handpiece is connected and a stainless steel block containing a Plexiglas block (inPlexiglass, Rome, Italy) against which the cutting efficiency of the instruments was tested. The length of the block cut in 1 minute was measured in a computerized program with a precision of 0.1 mm. Means and standard deviations of each group were calculated, and data were statistically analyzed with 1-way analysis of variance and Bonferroni test (P cutting efficiency than WaveOne Primary for both the movements used (P cutting efficiency than WaveOne instruments used with their proper reciprocating motion (P .05). Reciproc instruments demonstrated statistically higher cutting efficiency than WaveOne instruments. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Mesoscale heat waves induced by orography

    Directory of Open Access Journals (Sweden)

    I. Gladich

    2008-07-01

    Full Text Available This work is devoted to the analysis of an unusual and sudden thermal fluctuation that interested portions of Friuli Venezia Giulia (Italy during the night of 27 July 1983. The whole 1983 summer was extremely warm in Europe and in particular on the Italian peninsula, from the Alps down to Sicily. Nevertheless, the day of 27 July 1983 in Friuli Venezia Giulia deserves special attention because the observed maximum temperatures did not occur during day-time but during night-time (from 23:00 up to 24:00 LT, 21:00–22:00 UTC. Peaks of 34.8°C and values of relative humidity of the order of 28% were registered by the official network of weather stations. This event interested mainly the central-eastern part of the plain of Friuli Venezia Giulia, a few kilometers far from the Slovenian border and relieves. The thermal anomalies lasted up to an hour, then temperatures decreased toward values more usual for the climate of the month. The study of this event is carried out with the aid of the AR-WRF numerical atmospheric model, initialized through the ECMWF analysis. The numerical simulations highlight the important role played by orography, jointly with the peculiar thermal structure of the atmosphere, for the enhancing of the internal wave pattern over that area. According to the sensitivity studies realized, the amplification of the internal wave pattern might represent a possible explanation for that meteorological enigma.

  13. Can heat waves change the trophic role of the world's most invasive crayfish? Diet shifts in Procambarus clarkii.

    Science.gov (United States)

    Carreira, Bruno M; Segurado, Pedro; Laurila, Anssi; Rebelo, Rui

    2017-01-01

    In the Mediterranean basin, the globally increasing temperatures are expected to be accompanied by longer heat waves. Commonly assumed to benefit cold-limited invasive alien species, these climatic changes may also change their feeding preferences, especially in the case of omnivorous ectotherms. We investigated heat wave effects on diet choice, growth and energy reserves in the invasive red swamp crayfish, Procambarus clarkii. In laboratory experiments, we fed juvenile and adult crayfish on animal, plant or mixed diets and exposed them to a short or a long heat wave. We then measured crayfish survival, growth, body reserves and Fulton's condition index. Diet choices of the crayfish maintained on the mixed diet were estimated using stable isotopes (13C and 15N). The results suggest a decreased efficiency of carnivorous diets at higher temperatures, as juveniles fed on the animal diet were unable to maintain high growth rates in the long heat wave; and a decreased efficiency of herbivorous diets at lower temperatures, as juveniles in the cold accumulated less body reserves when fed on the plant diet. Heat wave treatments increased the assimilation of plant material, especially in juveniles, allowing them to sustain high growth rates in the long heat wave. Contrary to our expectations, crayfish performance decreased in the long heat wave, suggesting that Mediterranean summer heat waves may have negative effects on P. clarkii and that they are unlikely to boost its populations in this region. Although uncertain, it is possible that the greater assimilation of the plant diet resulted from changes in crayfish feeding preferences, raising the hypotheses that i) heat waves may change the predominant impacts of this keystone species and ii) that by altering species' trophic niches, climate change may alter the main impacts of invasive alien species.

  14. Can heat waves change the trophic role of the world's most invasive crayfish? Diet shifts in Procambarus clarkii.

    Directory of Open Access Journals (Sweden)

    Bruno M Carreira

    Full Text Available In the Mediterranean basin, the globally increasing temperatures are expected to be accompanied by longer heat waves. Commonly assumed to benefit cold-limited invasive alien species, these climatic changes may also change their feeding preferences, especially in the case of omnivorous ectotherms. We investigated heat wave effects on diet choice, growth and energy reserves in the invasive red swamp crayfish, Procambarus clarkii. In laboratory experiments, we fed juvenile and adult crayfish on animal, plant or mixed diets and exposed them to a short or a long heat wave. We then measured crayfish survival, growth, body reserves and Fulton's condition index. Diet choices of the crayfish maintained on the mixed diet were estimated using stable isotopes (13C and 15N. The results suggest a decreased efficiency of carnivorous diets at higher temperatures, as juveniles fed on the animal diet were unable to maintain high growth rates in the long heat wave; and a decreased efficiency of herbivorous diets at lower temperatures, as juveniles in the cold accumulated less body reserves when fed on the plant diet. Heat wave treatments increased the assimilation of plant material, especially in juveniles, allowing them to sustain high growth rates in the long heat wave. Contrary to our expectations, crayfish performance decreased in the long heat wave, suggesting that Mediterranean summer heat waves may have negative effects on P. clarkii and that they are unlikely to boost its populations in this region. Although uncertain, it is possible that the greater assimilation of the plant diet resulted from changes in crayfish feeding preferences, raising the hypotheses that i heat waves may change the predominant impacts of this keystone species and ii that by altering species' trophic niches, climate change may alter the main impacts of invasive alien species.

  15. Heat Waves, Droughts, and Preferences for Environmental Policy

    Science.gov (United States)

    Owen, Ann L.; Conover, Emily; Videras, Julio; Wu, Stephen

    2012-01-01

    Using data from a new household survey on environmental attitudes, behaviors, and policy preferences, we find that current weather conditions affect preferences for environmental regulation. Individuals who have recently experienced extreme weather (heat waves or droughts) are more likely to support laws to protect the environment. We find…

  16. Impact of simulated heat waves on soybean physiology and yield

    Science.gov (United States)

    With increases in mean global temperatures and associated climate change, extreme temperature events are predicted to increase in both intensity and frequency. Despite the clearly documented negative public health impacts of heat waves, the impact on physiology and yields of key agricultural species...

  17. Responses of tree species to heat waves and extreme heat events.

    Science.gov (United States)

    Teskey, Robert; Wertin, Timothy; Bauweraerts, Ingvar; Ameye, Maarten; McGuire, Mary Anne; Steppe, Kathy

    2015-09-01

    The number and intensity of heat waves has increased, and this trend is likely to continue throughout the 21st century. Often, heat waves are accompanied by drought conditions. It is projected that the global land area experiencing heat waves will double by 2020, and quadruple by 2040. Extreme heat events can impact a wide variety of tree functions. At the leaf level, photosynthesis is reduced, photooxidative stress increases, leaves abscise and the growth rate of remaining leaves decreases. In some species, stomatal conductance increases at high temperatures, which may be a mechanism for leaf cooling. At the whole plant level, heat stress can decrease growth and shift biomass allocation. When drought stress accompanies heat waves, the negative effects of heat stress are exacerbated and can lead to tree mortality. However, some species exhibit remarkable tolerance to thermal stress. Responses include changes that minimize stress on photosynthesis and reductions in dark respiration. Although there have been few studies to date, there is evidence of within-species genetic variation in thermal tolerance, which could be important to exploit in production forestry systems. Understanding the mechanisms of differing tree responses to extreme temperature events may be critically important for understanding how tree species will be affected by climate change. © 2014 John Wiley & Sons Ltd.

  18. The impact of heat waves on children's health: a systematic review

    Science.gov (United States)

    Xu, Zhiwei; Sheffield, Perry E.; Su, Hong; Wang, Xiaoyu; Bi, Yan; Tong, Shilu

    2014-03-01

    Young children are thought to be particularly sensitive to heat waves, but relatively less research attention has been paid to this field to date. A systematic review was conducted to elucidate the relationship between heat waves and children's health. Literature published up to August 2012 were identified using the following MeSH terms and keywords: "heatwave", "heat wave", "child health", "morbidity", "hospital admission", "emergency department visit", "family practice", "primary health care", "death" and "mortality". Of the 628 publications identified, 12 met the selection criteria. The existing literature does not consistently suggest that mortality among children increases significantly during heat waves, even though infants were associated with more heat-related deaths. Exposure to heat waves in the perinatal period may pose a threat to children's health. Pediatric diseases or conditions associated with heat waves include renal disease, respiratory disease, electrolyte imbalance and fever. Future research should focus on how to develop a consistent definition of a heat wave from a children's health perspective, identifying the best measure of children's exposure to heat waves, exploring sensitive outcome measures to quantify the impact of heat waves on children, evaluating the possible impacts of heat waves on children's birth outcomes, and understanding the differences in vulnerability to heat waves among children of different ages and from different income countries. Projection of the children's disease burden caused by heat waves under climate change scenarios, and development of effective heat wave mitigation and adaptation strategies that incorporate other child protective health measures, are also strongly recommended.

  19. Syndromic surveillance and heat wave morbidity: a pilot study based on emergency departments in France

    Directory of Open Access Journals (Sweden)

    Filleul Laurent

    2009-02-01

    Full Text Available Abstract Background The health impacts of heat waves are serious and have prompted the development of heat wave response plans. Even when they are efficient, these plans are developed to limit the health effects of heat waves. This study was designed to determine relevant indicators related to health effects of heat waves and to evaluate the ability of a syndromic surveillance system to monitor variations in the activity of emergency departments over time. The study uses data collected during the summer 2006 when a new heat wave occurred in France. Methods Data recorded from 49 emergency departments since July 2004, were transmitted daily via the Internet to the French Institute for Public Health Surveillance. Items collected on patients included diagnosis (ICD10 codes, outcome, and age. Statistical t-tests were used to compare, for several health conditions, the daily averages of patients within different age groups and periods (whether 'on alert' or 'off alert'. Results A limited number of adverse health conditions occurred more frequently during hot period: dehydration, hyperthermia, malaise, hyponatremia, renal colic, and renal failure. Over all health conditions, the total number of patients per day remained equal between the 'on alert' and 'off alert' periods (4,557.7/day vs. 4,511.2/day, but the number of elderly patients increased significantly during the 'on alert' period relative to the 'off alert' period (476.7/day vs. 446.2/day p Conclusion Our results show the interest to monitor specific indicators during hot periods and to focus surveillance efforts on the elderly. Syndromic surveillance allowed the collection of data in real time and the subsequent optimization of the response by public health agencies. This method of surveillance should therefore be considered as an essential part of efforts to prevent the health effects of heat waves.

  20. On the construction of heat wave in symmetric case

    Science.gov (United States)

    Kazakov, A. L.; Lempert, A. A.

    2016-06-01

    A nonlinear second-order parabolic equation with two variables is considered. Under additional conditions, this equation can be interpreted as the porous medium equation in case of dependence of the unknown function on two variables: time and distance from the origin. The equation has a wide variety of applications in continuum mechanics, for example, it is applicable for mathematical modeling of filtration of ideal polytropic gas in porous media or heat conduction. The authors deal with a special solutions which are usually called heat waves. A special feature of such solution is that it consists of two continuously joined solutions. The first of them is trivial and the second one is nonnegative. The heat wave solution can have discontinuous derivatives on the line of joint which is called the front of heat wave, i.e. smoothness of the solution, generally speaking, is broken. The most natural problem which has such solutions is the so-called “the Sakharov problem of the initiation of a heat wave”. New solutions of the problem in the form of multiple power series for physical variables are constructed. The coefficients of the series are obtained from tridiagonal systems of linear algebraic equations. Herewith, the elements of matrices of this systems depend on the matrix order and the condition of the diagonal dominance is not fulfilled. The recurrent formulas for the coefficients are suggested.

  1. Probability of US Heat Waves Affected by a Subseasonal Planetary Wave Pattern

    Science.gov (United States)

    Teng, Haiyan; Branstator, Grant; Wang, Hailan; Meehl, Gerald A.; Washington, Warren M.

    2013-01-01

    Heat waves are thought to result from subseasonal atmospheric variability. Atmospheric phenomena driven by tropical convection, such as the Asian monsoon, have been considered potential sources of predictability on subseasonal timescales. Mid-latitude atmospheric dynamics have been considered too chaotic to allow significant prediction skill of lead times beyond the typical 10-day range of weather forecasts. Here we use a 12,000-year integration of an atmospheric general circulation model to identify a pattern of subseasonal atmospheric variability that can help improve forecast skill for heat waves in the United States. We find that heat waves tend to be preceded by 15-20 days by a pattern of anomalous atmospheric planetary waves with a wavenumber of 5. This circulation pattern can arise as a result of internal atmospheric dynamics and is not necessarily linked to tropical heating.We conclude that some mid-latitude circulation anomalies that increase the probability of heat waves are predictable beyond the typical weather forecast range.

  2. The impact of heat transfer on Murphree tray efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Kaeser, M.; Pritchard, C.L. [University of Edinburgh (United Kingdom). Institute for Energy Systems

    2006-12-15

    This work features the experimental determination of heat transfer coefficients and Murphree tray efficiencies on a diabatic (heat-transferring) distillation tray. The present investigation, focussing on the impact of heat transfer on sieve tray performance, is part of a long-term project on heat integrated distillation columns (HIDiC). Heat transfer coefficients and tray efficiencies have been determined experimentally for the methanol/water system in a 150mm diameter distillation column. The heat-transferring tray was operated in both heating and cooling modes, with heat fluxes up to 50 and 100kWm{sup -2}, respectively. The experimental data from these diabatic experiments were compared with data obtained from the same column in adiabatic mode and were correlated with the vapour velocity and the heat flux to/from the tray. (author)

  3. Practical and efficient magnetic heat pump

    Science.gov (United States)

    Brown, G. V.

    1978-01-01

    Method for pumping heat magnetically at room temperature is more economical than existing refrigeration systems. Method uses natural magneto-thermal effect of gadolinium metal to establish temperature gradient across length of tube. Regenerative cyclic process in which gadolinium sample is magnetized and gives off heat at one end of tube, and then is demagnetized at other end to absorb heat has established temperature gradients of 144 degrees F in experiments near room temperature. Other materials with large magnetothermal effects can be used below room temperature. Possible commercial applications include freeze-drying and food processing, cold storage, and heating and cooling of buildings, plants, and ships.

  4. Efficient algorithms for non-linear four-wave interactions

    NARCIS (Netherlands)

    Van Vledder, G.P.

    2012-01-01

    This paper addresses the on-going activities in the development of efficient methods for computing the non-linear four-wave interactions in operational discrete third-generation wind-wave models. It is generally assumed that these interactions play an important role in the evolution of wind

  5. Development of slow and fast wave coupling and heating from the C-Stellarator to NSTX

    Directory of Open Access Journals (Sweden)

    Hosea Joel

    2017-01-01

    Full Text Available A historical perspective on key discoveries which contributed to understanding the properties of coupling both slow and fast waves and the effects on plasma heating and current drive will be presented. Important steps made include the demonstration that the Alfven resonance was in fact a mode conversion on the C-stellarator, that toroidal m = -1 eigenmodes were excited in toroidal geometry and impurity influx caused the Z mode on the ST tokamak, that the H minority regime provided strong heating and that 3He minority could be used as well on PLT, that the 2nd harmonic majority tritium regime was viable on TFTR, and that high harmonic fast wave heating was efficient when the SOL losses were avoided on NSTX.

  6. Development of slow and fast wave coupling and heating from the C-Stellarator to NSTX

    Science.gov (United States)

    Hosea, Joel

    2017-10-01

    A historical perspective on key discoveries which contributed to understanding the properties of coupling both slow and fast waves and the effects on plasma heating and current drive will be presented. Important steps made include the demonstration that the Alfven resonance was in fact a mode conversion on the C-stellarator, that toroidal m = -1 eigenmodes were excited in toroidal geometry and impurity influx caused the Z mode on the ST tokamak, that the H minority regime provided strong heating and that 3He minority could be used as well on PLT, that the 2nd harmonic majority tritium regime was viable on TFTR, and that high harmonic fast wave heating was efficient when the SOL losses were avoided on NSTX.

  7. Finite-size effect on optimal efficiency of heat engines

    Science.gov (United States)

    Tajima, Hiroyasu; Hayashi, Masahito

    2017-07-01

    The optimal efficiency of quantum (or classical) heat engines whose heat baths are n -particle systems is given by the strong large deviation. We give the optimal work extraction process as a concrete energy-preserving unitary time evolution among the heat baths and the work storage. We show that our optimal work extraction turns the disordered energy of the heat baths to the ordered energy of the work storage, by evaluating the ratio of the entropy difference to the energy difference in the heat baths and the work storage, respectively. By comparing the statistical mechanical optimal efficiency with the macroscopic thermodynamic bound, we evaluate the accuracy of the macroscopic thermodynamics with finite-size heat baths from the statistical mechanical viewpoint. We also evaluate the quantum coherence effect on the optimal efficiency of the cycle processes without restricting their cycle time by comparing the classical and quantum optimal efficiencies.

  8. Overly persistent circulation in climate models contributes to overestimated frequency and duration of heat waves and cold spells

    Science.gov (United States)

    Plavcová, Eva; Kyselý, Jan

    2016-05-01

    The study examines links of summer heat waves and winter cold spells in Central Europe to atmospheric circulation and specifically its persistence in an ensemble of regional climate models (RCMs). We analyse 13 RCMs driven by the ERA-40 reanalysis and compare them against observations over reference period 1971-2000. Using objective classification of circulation types and an efficiency coefficient with a block resampling test, we identify circulation types significantly conducive to heat waves and cold spells. We show that the RCMs have a stronger tendency to group together days with very high or low temperature and tend to simulate too many heat waves and cold spells, especially those lasting 5 days and more. Circulation types conducive to heat waves in summer are characterized by anticyclonic, southerly and easterly flow, with increasing importance of warm advection during heat waves. Winter cold spells are typically associated with easterly and anticyclonic flow, and the onset of cold spells tends to be linked to northerly and cyclonic flow with cold advection. The RCMs are generally able to reproduce the links between circulation and heat waves or cold spells, including the radiation-to-advection effect for heat waves and the opposite advection-to-radiation effect for cold spells. They capture relatively well also changes of mean temperature anomalies during sequences of given circulation types, namely the tendency towards temperature increase (decrease) during those types conducive to heat waves (cold spells). Since mean lengths of all circulation supertypes are overestimated in the RCMs, we conclude that the overly persistent circulation in climate models contributes to the overestimated frequency of long heat waves and cold spells. As these biases are rather general among the examined RCMs and similar drawbacks are likely to be manifested in climate model simulations for the twenty-first century, the results also suggest that climate change scenarios for

  9. The urban heat island and its impact on heat waves and human health in Shanghai.

    Science.gov (United States)

    Tan, Jianguo; Zheng, Youfei; Tang, Xu; Guo, Changyi; Li, Liping; Song, Guixiang; Zhen, Xinrong; Yuan, Dong; Kalkstein, Adam J; Li, Furong

    2010-01-01

    With global warming forecast to continue into the foreseeable future, heat waves are very likely to increase in both frequency and intensity. In urban regions, these future heat waves will be exacerbated by the urban heat island effect, and will have the potential to negatively influence the health and welfare of urban residents. In order to investigate the health effects of the urban heat island (UHI) in Shanghai, China, 30 years of meteorological records (1975-2004) were examined for 11 first- and second-order weather stations in and around Shanghai. Additionally, automatic weather observation data recorded in recent years as well as daily all-cause summer mortality counts in 11 urban, suburban, and exurban regions (1998-2004) in Shanghai have been used. The results show that different sites (city center or surroundings) have experienced different degrees of warming as a result of increasing urbanization. In turn, this has resulted in a more extensive urban heat island effect, causing additional hot days and heat waves in urban regions compared to rural locales. An examination of summer mortality rates in and around Shanghai yields heightened heat-related mortality in urban regions, and we conclude that the UHI is directly responsible, acting to worsen the adverse health effects from exposure to extreme thermal conditions.

  10. On the Efficiency of a Quantum Heat Engine

    OpenAIRE

    Ramezani, Mehdi; Golshani, Mehdi

    2017-01-01

    The efficiency of a Carnot Heat Engine enhances whenever one increases the temperature of the hot reservoir or decreases the temperature of the cold reservoir. We show that for a Quantum Heat Engine, decreasing the temperature of the cold reservoir may not enhance the efficiency of the heat engine. This is because at low temperatures the small internal interaction energy of the working substance becomes comparable with thermal fluctuation energy. Thus the internal interaction reduces the effi...

  11. The effect of heat waves on dairy cow mortality.

    Science.gov (United States)

    Vitali, A; Felici, A; Esposito, S; Bernabucci, U; Bertocchi, L; Maresca, C; Nardone, A; Lacetera, N

    2015-07-01

    This study investigated the mortality of dairy cows during heat waves. Mortality data (46,610 cases) referred to dairy cows older than 24mo that died on a farm from all causes from May 1 to September 30 during a 6-yr period (2002-2007). Weather data were obtained from 12 weather stations located in different areas of Italy. Heat waves were defined for each weather station as a period of at least 3 consecutive days, from May 1 to September 30 (2002-2007), when the daily maximum temperature exceeded the 90th percentile of the reference distribution (1971-2000). Summer days were classified as days in heat wave (HW) or not in heat wave (nHW). Days in HW were numbered to evaluate the relationship between mortality and length of the wave. Finally, the first 3 nHW days after the end of a heat wave were also considered to account for potential prolonged effects. The mortality risk was evaluated using a case-crossover design. A conditional logistic regression model was used to calculate odds ratio and 95% confidence interval for mortality recorded in HW compared with that recorded in nHW days pooled and stratified by duration of exposure, age of cows, and month of occurrence. Dairy cows mortality was greater during HW compared with nHW days. Furthermore, compared with nHW days, the risk of mortality continued to be higher during the 3 d after the end of HW. Mortality increased with the length of the HW. Considering deaths stratified by age, cows up to 28mo were not affected by HW, whereas all the other age categories of older cows (29-60, 61-96, and >96mo) showed a greater mortality when exposed to HW. The risk of death during HW was higher in early summer months. In particular, the highest risk of mortality was observed during June HW. Present results strongly support the implementation of adaptation strategies which may limit heat stress-related impairment of animal welfare and economic losses in dairy cow farm during HW. Copyright © 2015 American Dairy Science

  12. Heating of solar coronal holes by reflected Alfven waves

    Science.gov (United States)

    Moore, R. L.; Musielak, Z. E.; Suess, S. T.; An, C.-H.

    1992-01-01

    As a continuation of the work of Moore et al. (1991), who found evidence that coronal holes are heated by Alfven waves that are reflected back down within the coronal holes, this paper shows that to demonstrate this evidence, it is only necessary to consider a subset of the Moore et al. models, namely, those having radial magnetic field. Using these models, it is shown that the Alfven velocity is not constant in the atmosphere of coronal holes, but changes with height (or radius), causing downward reflection of all upward Alfven waves of sufficiently long wavelength (or period).

  13. Improved district heating substation efficiency with a new control strategy

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, Jonas; Delsing, Jerker; van Deventer, Jan [Div. of EISLAB, Dept. of Computer Science and Electrical Engineering, Luleaa University of Technology, 97187 Luleaa (Sweden)

    2010-06-15

    In this paper, we describe a new alternative control approach for indirectly connected district heating substations. Simulations results showed that the new approach results in an increased {delta} T across the substation. Results were obtained for both ideal and non-ideal operation of the system, meaning that less water must be pumped through the district heating network, and a higher overall fuel efficiency can be obtained in the district heating power plants. When a higher fuel efficiency is achieved, the usage of primary fuel sources can be reduced. Improved efficiency also increases the effective heat transfer capacity of a district heating network, allowing more customers to be connected to an existing network without increasing the heating plant or network capacity. Also, if combined heat and power plants are used to produce the heat, the increased {delta} T will result in a further improved overall fuel efficiency, as more electricity can be produced with colder cooling water. The idea behind the new control method is to consider the temperature of the water supplying the district heating substation with heat, often referred to as the primary supply temperature. This represents a logical next step, as currently, the only parameter generally taken into account or measured when controlling the temperature level of the radiator circuit is the local outdoor temperature. In this paper we show how the primary supply temperature together with thermodynamic knowledge of the building can be used to maximize the {delta} T across the district heating substation. (author)

  14. Dynamical effects of vegetation on the 2003 summer heat waves

    Science.gov (United States)

    Stéfanon, M.

    2012-04-01

    Dynamical effects of vegetation on the 2003 summer heat waves Marc Stéfanon(1), Philippe Drobinski(1), Fabio D'Andrea(1), Nathalie de Noblet(2) (1) IPSL/LMD, France; (2) IPSL/LSCE, France The land surface model (LSM) in regional climate models (RCMs) plays a key role in energy and water exchanges between land and atmosphere. The vegetation can affect these exchanges through physical, biophysical and bio-geophysical mechanisms. It participates to evapo-transpiration process which determines the partitioning of net radiation between sensible and latent heat flux, through water evaporation from soil throughout the entire root system. For seasonal timescale leaf cover change induced leaf-area index (LAI) and albedo changes, impacting the Earth's radiative balance. In addition, atmospheric chemistry and carbon concentration has a direct effect on plant stomatal structure, the main exchange interface with the atmosphere. Therefore the surface energy balance is intimately linked to the carbon cycle and vegetation conditions and an accurate representation of the Earth's surface is required to improve the performance of RCMs. It is even more crucial for extreme events as heat waves and droughts which display highly nonlinear behaviour. If triggering of heat waves is determined by the large scale, local coupled processes over land can amplify or inhibit heat trough several feedback mechanism. One set of two simulation has been conducted with WRF, using different LSMs. They aim to study drought and vegetation effect on the dynamical and hydrological processes controlling the occurrence and life cycle of heat waves In the MORCE plateform, the dynamical global vegetation model (DGVM) ORCHIDEE is implemented in the atmospheric module WRF. ORCHIDEE is based on three different modules. The first module, called SECHIBA, describes the fast processes such as exchanges of energy and water between the atmosphere and the biosphere, and the soil water budget. The phenology and carbon

  15. Using forecast and observed weather data to assess performance of forecast products in identifying heat waves and estimating heat wave effects on mortality.

    Science.gov (United States)

    Zhang, Kai; Chen, Yeh-Hsin; Schwartz, Joel D; Rood, Richard B; O'Neill, Marie S

    2014-09-01

    Heat wave and health warning systems are activated based on forecasts of health-threatening hot weather. We estimated heat-mortality associations based on forecast and observed weather data in Detroit, Michigan, and compared the accuracy of forecast products for predicting heat waves. We derived and compared apparent temperature (AT) and heat wave days (with heat waves defined as ≥ 2 days of daily mean AT ≥ 95th percentile of warm-season average) from weather observations and six different forecast products. We used Poisson regression with and without adjustment for ozone and/or PM10 (particulate matter with aerodynamic diameter ≤ 10 μm) to estimate and compare associations of daily all-cause mortality with observed and predicted AT and heat wave days. The 1-day-ahead forecast of a local operational product, Revised Digital Forecast, had about half the number of false positives compared with all other forecasts. On average, controlling for heat waves, days with observed AT = 25.3°C were associated with 3.5% higher mortality (95% CI: -1.6, 8.8%) than days with AT = 8.5°C. Observed heat wave days were associated with 6.2% higher mortality (95% CI: -0.4, 13.2%) than non-heat wave days. The accuracy of predictions varied, but associations between mortality and forecast heat generally tended to overestimate heat effects, whereas associations with forecast heat waves tended to underestimate heat wave effects, relative to associations based on observed weather metrics. Our findings suggest that incorporating knowledge of local conditions may improve the accuracy of predictions used to activate heat wave and health warning systems.

  16. High Efficiency Microchannel Diamond Heat Sinks Project

    Data.gov (United States)

    National Aeronautics and Space Administration — While absolute power levels in microelectronic devices are relatively modest (a few tens to a few hundred watts), heat fluxes can be significant (~50 W/cm2 in...

  17. On an efficient shock wave generation mechanism in the quiet solar transition region

    Science.gov (United States)

    Dunin-Barkovskaya, O. V.; Somov, B. V.

    2017-08-01

    Two competing fundamental hypotheses are usually postulated in the solar coronal heating problem: heating by nanoflares and heating by waves. In the latter it is assumed that acoustic and magnetohydrodynamic disturbances whose amplitude grows as they propagate in a medium with a decreasing density come from the convection zone. The shock waves forming in the process heat up the corona. In this paper we draw attention to yet another very efficient shock wave generation process that can be realized under certain conditions typical for quiet regions on the Sun. In the approximation of stationary dissipative hydrodynamics we show that a shock wave can be generated in the quiet solar chromosphere-corona transition region by the fall of plasma from the corona into the chromosphere. This shock wave is directed upward, and its dissipation in the corona returns part of the kinetic energy of the falling plasma to the thermal energy of the corona. We discuss the prospects for developing a quantitative nonstationary model of the phenomenon.

  18. A new way to convert Alfven waves into heat in solar coronal holes - Intermittent magnetic levitation

    Science.gov (United States)

    Moore, R. L.; Hammer, R.; Musielak, Z. E.; Suess, S. T.; An, C.-H.

    1992-01-01

    In our recent analysis of Alfven wave reflection in solar coronal holes, we found evidence that coronal holes are heated by reflected Alfven waves. This result suggests that the reflection is inherent to the process that dissipates these Alfven waves into heat. We propose a novel dissipation process that is driven by the reflection, and that plausibly dominates the heating in coronal holes.

  19. Diamond Heat-Spreader for Submillimeter-Wave Frequency Multipliers

    Science.gov (United States)

    Lin, Robert H.; Schlecht, Erich T.; Chattopadhyay, Goutam; Gill, John J.; Mehdi, Imran; Siegel, Peter H.; Ward, John S.; Lee, Choonsup; Thomas, Bertrand C.; Maestrini, Alain

    2010-01-01

    The planar GaAs Shottky diode frequency multiplier is a critical technology for the local oscillator (LO) for submillimeter- wave heterodyne receivers due to low mass, tenability, long lifetime, and room-temperature operation. The use of a W-band (75-100 GHz) power amplifier followed by a frequency multiplier is the most common for submillimeter-wave sources. Its greatest challenge is to provide enough input power to the LO for instruments onboard future planetary missions. Recently, JPL produced 800 mW at 92.5 GHz by combining four MMICs in parallel in a balanced configuration. As more power at W-band is available to the multipliers, their power-handling capability be comes more important. High operating temperatures can lead to degradation of conversion efficiency or catastrophic failure. The goal of this innovation is to reduce the thermal resistance by attaching diamond film as a heat-spreader on the backside of multipliers to improve their power-handling capability. Polycrystalline diamond is deposited by hot-filament chemical vapor deposition (CVD). This diamond film acts as a heat-spreader to both the existing 250- and 300-GHz triplers, and has a high thermal conductivity (1,000-1,200 W/mK). It is approximately 2.5 times greater than copper (401 W/mK) and 20 times greater than GaAs (46 W/mK). It is an electrical insulator (resistivity approx. equals 10(exp 15) Ohms-cm), and has a low relative dielectric constant of 5.7. Diamond heat-spreaders reduce by at least 200 C at 250 mW of input power, compared to the tripler without diamond, according to thermal simulation. This superior thermal management provides a 100-percent increase in power-handling capability. For example, with this innovation, 40-mW output power has been achieved from a 250-GHz tripler at 350-mW input power, while the previous triplers, without diamond, suffered catastrophic failures. This breakthrough provides a stepping-stone for frequency multipliers-based LO up to 3 THz. The future work

  20. Tropical Gravity Wave Momentum Fluxes and Latent Heating Distributions

    Science.gov (United States)

    Geller, Marvin A.; Zhou, Tiehan; Love, Peter T.

    2015-01-01

    Recent satellite determinations of global distributions of absolute gravity wave (GW) momentum fluxes in the lower stratosphere show maxima over the summer subtropical continents and little evidence of GW momentum fluxes associated with the intertropical convergence zone (ITCZ). This seems to be at odds with parameterizations forGWmomentum fluxes, where the source is a function of latent heating rates, which are largest in the region of the ITCZ in terms of monthly averages. The authors have examined global distributions of atmospheric latent heating, cloud-top-pressure altitudes, and lower-stratosphere absolute GW momentum fluxes and have found that monthly averages of the lower-stratosphere GW momentum fluxes more closely resemble the monthly mean cloud-top altitudes rather than the monthly mean rates of latent heating. These regions of highest cloud-top altitudes occur when rates of latent heating are largest on the time scale of cloud growth. This, plus previously published studies, suggests that convective sources for stratospheric GW momentum fluxes, being a function of the rate of latent heating, will require either a climate model to correctly model this rate of latent heating or some ad hoc adjustments to account for shortcomings in a climate model's land-sea differences in convective latent heating.

  1. Persistent heat waves in Eastern China: Dynamical processes and trends

    Science.gov (United States)

    Freychet, Nicolas; Tett, Simon; Wang, Jun; Hegerl, Gabriel

    2017-04-01

    Recent trends (1979-2010) in summer heat waves (HW) over Central-Eastern China and their atmospheric drivers are investigated using the ERA Interim re-analysis. We focus on regional scale (105E-125E,30N-40N) and persistent events (more than 5 days), thus threatening for a large population. A composite analysis is used to highlight the main dynamical processes associated with such events, and lag-composites show the evolution of the circulation before and after the heat waves. A particular attention is made on the possible feedbacks that can extend the length of the events. The trend in the occurrence of such events is analysed and we conducted a simple attribution analysis to separate the changes in the background temperature and the possible changes in the atmospheric anomalies.

  2. Highly Efficient Wave-Front Reshaping of Surface Waves with Dielectric Metawalls

    Science.gov (United States)

    Dong, Shaohua; Zhang, Yu; Guo, Huijie; Duan, Jingwen; Guan, Fuxin; He, Qiong; Zhao, Haibin; Zhou, Lei; Sun, Shulin

    2018-01-01

    Controlling the wave fronts of surface waves (including surface-plamon polaritons and their equivalent counterparts) at will is highly important in photonics research, but the available mechanisms suffer from the issues of low efficiency, bulky size, and/or limited functionalities. Inspired by recent studies of metasurfaces that can freely control the wave fronts of propagating waves, we propose to use metawalls placed on a plasmonic surface to efficiently reshape the wave fronts of incident surface waves (SWs). Here, the metawall is constructed by specifically designed meta-atoms that can reflect SWs with desired phases and nearly unit amplitudes. As a proof of concept, we design and fabricate a metawall in the microwave regime (around 12 GHz) that can anomalously reflect the SWs following the generalized Snell's law with high efficiency (approximately 70%). Our results, in excellent agreement with full-wave simulations, provide an alternative yet efficient way to control the wave fronts of SWs in different frequency domains. We finally employ full-wave simulations to demonstrate a surface-plasmon-polariton focusing effect at telecom wavelength based on our scheme.

  3. Multivariate Statistical Modelling of Drought and Heat Wave Events

    Science.gov (United States)

    Manning, Colin; Widmann, Martin; Vrac, Mathieu; Maraun, Douglas; Bevaqua, Emanuele

    2016-04-01

    Multivariate Statistical Modelling of Drought and Heat Wave Events C. Manning1,2, M. Widmann1, M. Vrac2, D. Maraun3, E. Bevaqua2,3 1. School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK 2. Laboratoire des Sciences du Climat et de l'Environnement, (LSCE-IPSL), Centre d'Etudes de Saclay, Gif-sur-Yvette, France 3. Wegener Center for Climate and Global Change, University of Graz, Brandhofgasse 5, 8010 Graz, Austria Compound extreme events are a combination of two or more contributing events which in themselves may not be extreme but through their joint occurrence produce an extreme impact. Compound events are noted in the latest IPCC report as an important type of extreme event that have been given little attention so far. As part of the CE:LLO project (Compound Events: muLtivariate statisticaL mOdelling) we are developing a multivariate statistical model to gain an understanding of the dependence structure of certain compound events. One focus of this project is on the interaction between drought and heat wave events. Soil moisture has both a local and non-local effect on the occurrence of heat waves where it strongly controls the latent heat flux affecting the transfer of sensible heat to the atmosphere. These processes can create a feedback whereby a heat wave maybe amplified or suppressed by the soil moisture preconditioning, and vice versa, the heat wave may in turn have an effect on soil conditions. An aim of this project is to capture this dependence in order to correctly describe the joint probabilities of these conditions and the resulting probability of their compound impact. We will show an application of Pair Copula Constructions (PCCs) to study the aforementioned compound event. PCCs allow in theory for the formulation of multivariate dependence structures in any dimension where the PCC is a decomposition of a multivariate distribution into a product of bivariate components modelled using copulas. A

  4. Four-wave mixing in quantum dot SOAs: Theory of carrier heating

    Science.gov (United States)

    Flayyih, Ahmed H.; Al-Shatravi, Ali Gehad; Al-Khursan, Amin H.

    Carrier heating (CH) theory in a four-wave mixing quantum dot structure has been investigated. The impact of wetting layer (WL) carrier density, CH time constant, effective intraband relaxation time have been examined. The derived heat capacity for QD structure have (T-1) dependence. It is shown here that both WL carrier density and QD excited state (ES) occupation controls the overall nonlinear contributions. Then inclusion of WL and ES in the CH induces a new equilibrium reached at a faster recovery time. The proposed model yields results in a line with experiments at high carrier density reflecting the efficiency of our model.

  5. Heating by transverse waves in simulated coronal loops

    Science.gov (United States)

    Karampelas, K.; Van Doorsselaere, T.; Antolin, P.

    2017-08-01

    Context. Recent numerical studies of oscillating flux tubes have established the significance of resonant absorption in the damping of propagating transverse oscillations in coronal loops. The nonlinear nature of the mechanism has been examined alongside the Kelvin-Helmholtz instability, which is expected to manifest in the resonant layers at the edges of the flux tubes. While these two processes have been hypothesized to heat coronal loops through the dissipation of wave energy into smaller scales, the occurring mixing with the hotter surroundings can potentially hide this effect. Aims: We aim to study the effects of wave heating from driven and standing kink waves in a coronal loop. Methods: Using the MPI-AMRVAC code, we perform ideal, three dimensional magnetohydrodynamic (MHD) simulations of both (a) footpoint driven and (b) free standing oscillations in a straight coronal flux tube, in the presence of numerical resistivity. Results: We have observed the development of Kelvin-Helmholtz eddies at the loop boundary layer of all three models considered here, as well as an increase of the volume averaged temperature inside the loop. The main heating mechanism in our setups was Ohmic dissipation, as indicated by the higher values for the temperatures and current densities located near the footpoints. The introduction of a temperature gradient between the inner tube and the surrounding plasma, suggests that the mixing of the two regions, in the case of hotter environment, greatly increases the temperature of the tube at the site of the strongest turbulence, beyond the contribution of the aforementioned wave heating mechanism. Three movies associated to Fig. 1 are available in electronic form at http://www.aanda.org

  6. Periodic heat wave determination of thermal diffusivity of clays ...

    African Journals Online (AJOL)

    The responses of Ankaful, Tetegu (# 1 & 2) and Mamfe clays to periodic heat waves were analyzed to deter-mine the thermal diffusivity values. The temperature amplitude attenuated with depth of penetration, while the phase shift increased. The thermal diffusivity values ranged from 3.0 - 9.5 x 10P-7P mP2P/s by amplitude ...

  7. The 2011 marine heat wave in Cockburn Sound, southwest Australia

    Directory of Open Access Journals (Sweden)

    T. H. Rose

    2012-07-01

    Full Text Available Over 2000 km of Western Australian coastline experienced a significant marine heat wave in February and March 2011. Seawater temperature anomalies of +2–4 °C were recorded at a number of locations, and satellite-derived SSTs (sea surface temperatures were the highest on record. Here, we present seawater temperatures from southwestern Australia and describe, in detail, the marine climatology of Cockburn Sound, a large, multiple-use coastal embayment. We compared temperature and dissolved oxygen levels in 2011 with data from routine monitoring conducted from 2002–2010. A significant warming event, 2–4 °C in magnitude, persisted for > 8 weeks, and seawater temperatures at 10 to 20 m depth were significantly higher than those recorded in the previous 9 yr. Dissolved oxygen levels were depressed at most monitoring sites, being ~ 2 mg l−1 lower than usual in early March 2011. Ecological responses to short-term extreme events are poorly understood, but evidence from elsewhere along the Western Australian coastline suggests that the heat wave was associated with high rates of coral bleaching; fish, invertebrate and macroalgae mortalities; and algal blooms. However, there is a paucity of historical information on ecologically-sensitive habitats and taxa in Cockburn Sound, so that formal examinations of biological responses to the heat wave were not possible. The 2011 heat wave provided insights into conditions that may become more prevalent in Cockburn Sound, and elsewhere, if the intensity and frequency of short-term extreme events increases as predicted.

  8. Heat waves in Senegal : detection, characterization and associated processes.

    Science.gov (United States)

    Gnacoussa Sambou, Marie Jeanne; Janicot, Serge; Badiane, Daouda; Pohl, Benjamin; Dieng, Abdou L.; Gaye, Amadou T.

    2017-04-01

    Atmospheric configuration and synoptic evolution of patterns associated with Senegalese heat wave (HW) are examined on the period 1979-2014 using the Global Surface Summary of the Day (GSOD) observational database and ERA-Interim reanalysis. Since there is no objective and uniform definition of HW events, threshold methods based on atmospheric variables as daily maximum (Tmax) / minimum (Tmin) temperatures and daily mean apparent temperature (AT) are used to define HW threshold detection. Each criterion is related to a specific category of HW events: Tmax (warm day events), Tmin (warm night events) and AT (combining temperature and moisture). These definitions are used in order to characterize as well as possible the warm events over the Senegalese regions (oceanic versus continental region). Statistics on time evolution and spatial distribution of warm events are carried out over the 2 seasons of maximum temperature (March-May and October-November). For each season, a composite of HW events, as well as the most extended event over Senegal (as a case study) are analyzed using usual atmospheric fields (sea level pressure, geopotential height, total column water content, wind components, 2m temperature). This study is part of the project ACASIS (https://acasis.locean-ipsl.upmc.fr/doku.php) on heat waves occurrences over the Sahel and their impact on health. Keywords: heat wave, Senegal, ACASIS.

  9. Heat pumps; Synergy of high efficiency and low carbon electricity

    Energy Technology Data Exchange (ETDEWEB)

    Koike, Akio

    2010-09-15

    Heat pump is attracting wide attention for its high efficiency to utilize inexhaustible and renewable ambient heat in the environment. With its rapid innovation and efficiency improvement, this technology has a huge potential to reduce CO2 emissions by replacing currently widespread fossil fuel combustion systems to meet various heat demands from the residential, commercial and industrial sectors. Barriers to deployment such as low public awareness and a relatively long pay-back period do exist, so it is strongly recommended that each country implement policies to promote heat pumps as a renewable energy option and an effective method to combat global warming.

  10. Edge loss of high-harmonic fast-wave heating power in NSTX: a cylindrical model

    Science.gov (United States)

    Perkins, R. J.; Hosea, J. C.; Bertelli, N.; Taylor, G.; Wilson, J. R.

    2017-11-01

    Efficient high-harmonic fast-wave (HHFW) heating in the National Spherical Torus Experiment Upgrade (NSTX-U) would facilitate experiments in turbulence, transport, fast-ion studies, and more. However, previous HHFW operation in NSTX exhibited a large loss of fast-wave power to the divertor along the scrape-off layer field lines for edge densities above the fast-wave cutoff. It was postulated that the wave amplitude is enhanced in the scrape-off layer due to cavity-like modes, and that these enhanced fields drive sheath losses through RF rectification. As part of ongoing work to confirm this hypothesis, we have developed a cylindrical cold-plasma model to identify and understand scenarios where a substantial fraction of wave power is confined to the plasma periphery. We previously identified a peculiar class of modes, named annulus resonances, that conduct approximately half of their wave power in the periphery and can also account for a significant fraction of the total wave power. Here, we study the influence of annulus resonances on wave field reconstructions and find instances where annulus-resonant modes dominate the spectrum and trap over half of the total wave power at the edge. The work is part of an ongoing effort to determine the mechanism underlying these scrape-off layer losses in NSTX, identify optimal conditions for operation in NSTX-U, and predict whether similar losses occur for the ion-cyclotron minority heating scheme for both current experiments and future devices such as ITER.

  11. Enhanced continuous-wave four-wave mixing efficiency in nonlinear AlGaAs waveguides.

    Science.gov (United States)

    Apiratikul, Paveen; Wathen, Jeremiah J; Porkolab, Gyorgy A; Wang, Bohan; He, Lei; Murphy, Thomas E; Richardson, Christopher J K

    2014-11-03

    Enhancements of the continuous-wave four-wave mixing conversion efficiency and bandwidth are accomplished through the application of plasma-assisted photoresist reflow to reduce the sidewall roughness of sub-square-micron-modal area waveguides. Nonlinear AlGaAs optical waveguides with a propagation loss of 0.56 dB/cm demonstrate continuous-wave four-wave mixing conversion efficiency of -7.8 dB. Narrow waveguides that are fabricated with engineered processing produce waveguides with uncoated sidewalls and anti-reflection coatings that show group velocity dispersion of +0.22 ps²/m. Waveguides that are 5-mm long demonstrate broadband four-wave mixing conversion efficiencies with a half-width 3-dB bandwidth of 63.8-nm.

  12. Lightweight and Energy Efficient Heat Pump Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Future Spacecraft from the JPL will require increasingly sophisticated thermal control technology. A need exists for efficient, lightweight Vapor Compression Cycle...

  13. Fast and Efficient Approach in Surface Wave Analysis

    Science.gov (United States)

    Kanli, A. I.

    2010-12-01

    Fast and Efficient Approach in Surface Wave Analysis Ali Ismet KANLI Istanbul University, Engineering Faculty, Department of Geophysical Engineering, 34320, Avcilar Campus, Istanbul-Turkey, E-mail: kanli@istanbul.edu.tr Abstract: A two-step surface wave analysis method is proposed including both the MASW (Multi-channel Analysis of Surface Waves) and Micro-tremor based techniques. This is an integrated approach and the MASW survey data are gathered to obtain the shear wave velocity-depth information up to at least 30 meters by using a special type active seismic source called as SR-II or Kangaroo. In the second step, the microtremor data which are based on surface waves from seismic noise at each site are used to determine the shear-wave velocity-depth profiles. In the second step of the process, the multichannel analysis of surface waves data are given as constraints in the microtremor inversion process. This proposed algorithm allows us to calculate shear wave velocity-depth information with all geotechnical parameters from near surface to bedrock depths very fast and efficiently.

  14. The technological raw material heating furnaces operation efficiency improving issue

    Science.gov (United States)

    Paramonov, A. M.

    2017-08-01

    The issue of fuel oil applying efficiency improving in the technological raw material heating furnaces by means of its combustion intensification is considered in the paper. The technical and economic optimization problem of the fuel oil heating before combustion is solved. The fuel oil heating optimal temperature defining method and algorithm analytically considering the correlation of thermal, operating parameters and discounted costs for the heating furnace were developed. The obtained optimization functionality provides the heating furnace appropriate thermal indices achievement at minimum discounted costs. The carried out research results prove the expediency of the proposed solutions using.

  15. Atmospheric aerosol variability above the Paris Area during the 2015 heat wave - Comparison with the 2003 and 2006 heat waves

    Science.gov (United States)

    Chazette, Patrick; Totems, Julien; Shang, Xiaoxia

    2017-12-01

    The aerosol layers during the heat wave of July 2015 over Paris Area have been studied using a N2-Raman lidar with co- and cross-polarized channels. The lidar observations are examined to allow the identification of main aerosol types and their origins, in synergy with measurements of the AERONET sunphotometer network and back trajectory studies from the HYSPLIT model. The results are compatible with spaceborne observations of MODIS and CALIOP. As for previous heat waves of August 2003 and July 2006 occurring in France, the aerosol optical thickness is very large, up to 0.8 at the lidar wavelength of 355 nm (between 0.5 and 0.7 at 550 nm). However, air mass trajectories highlight that the observed aerosol layers may have multiple and diverse origins during the 2015 heat wave (North America, Northwest Africa, Southern and Northern Europe). Biomass burning, pollution and desert dust aerosols have been identified, using linear particle depolarization ratio, lidar ratio and analysis of back trajectories initiated at the altitudes and arrival times of the plumes. These layers are elevated and are shown to have little impact on surface aerosol concentrations (PM10 albedo distributions at 550 nm: 0.90 ± 0.03, 0.95 ± 0.02 and 0.93 ± 0.04 for 2003, 2006 and 2015, respectively.

  16. Regenerator heat exchanger – calculation of heat recovery efficiency and pressure loss

    DEFF Research Database (Denmark)

    Pomianowski, Michal Zbigniew; Heiselberg, Per Kvols

    Performance of heat exchangers is determined based on two main parameters: efficiency to exchange / recover heat and pressure loss due to friction between fluid and exchanger surfaces. These two parameters are contradicting each other which mean that the higher is efficiency the higher becomes...... pressure loss. The aim of the optimized design of heat exchanger is to reach the highest or the required heat efficiency and at the same time to keep pressure losses as low as possible keeping total exchanger size within acceptable size. In this report is presented analytical calculation method...... to calculate efficiency and pressure loss in the regenerator heat exchanger with a fixed matrix that will be used in the decentralized ventilation unit combined in the roof window. Moreover, this study presents sensitivity study of regenerator heat exchanger performance, taking into account, such parameters as...

  17. Impact of heat shock step on bacterial transformation efficiency.

    Science.gov (United States)

    Rahimzadeh, Maral; Sadeghizadeh, Majid; Najafi, Farhood; Arab, Seyed; Mobasheri, Hamid

    2016-12-01

    CaCl2 treatment followed by heat shock is the most common method for artificial transformation. Here, the cells were transformed using CaCl2 treatment either with heat shock (standard protocol) or without heat shock (lab protocol) to comprehend the difference in transformation efficiency. The BL21 strain of Escherichia coli (E. coli) was being susceptible using CaCl2 treatment. Some Cells were kept at -80 oC while the others were kept at 4 ˚C. Afterwards the susceptible cells were transformed using either standard or lab protocol. The transformation efficiency between cells experienced heat shock and those were not influenced by heat shock was almost the same. Moreover, regardless of transformation protocol, the cells kept at 4 ˚C were transformed more efficiently in compared to those were kept at -80 oC.

  18. Efficiency of Wave-Driven Rigid Body Rotation Toroidal Confinement

    CERN Document Server

    Rax, J -M; Fisch, N J

    2016-01-01

    The compensation of vertical drifts in toroidal magnetic fields through a wave-driven poloidal rotation is compared to compensation through the wave driven toroidal current generation to support the classical magnetic rotational transform. The advantages and drawbacks associated with the sustainment of a radial electric field are compared with those associated with the sustainment of a poloidal magnetic field both in terms of energy content and power dissipation. The energy content of a radial electric field is found to be smaller than the energy content of a poloidal magnetic field for a similar set of orbits. The wave driven radial electric field generation efficiency is similarly shown, at least in the limit of large aspect ratio, to be larger than the efficiency of wave-driven toroidal current generation.

  19. Future changes of temperature and heat waves in Ontario, Canada

    Science.gov (United States)

    Li, Zhong; Huang, Guohe; Huang, Wendy; Lin, Qianguo; Liao, Renfei; Fan, Yurui

    2017-05-01

    Apparent changes in the temperature patterns in recent years brought many challenges to the province of Ontario, Canada. As the need for adapting to climate change challenges increases, the development of reliable climate projections becomes a crucial task. In this study, a regional climate modeling system, Providing Regional Climates for Impacts Studies (PRECIS), is used to simulate the temperature patterns in Ontario. Three PRECIS runs with a resolution of 25 km × 25 km are carried out to simulate the present (1961-1990) temperature variations. There is a good match between the simulated and observed data, which validates the performance of PRECIS in reproducing temperature changes in Ontario. Future changes of daily maximum, mean, and minimum temperatures during the period 2071-2100 are then projected under the IPCC SRES A2 and B2 emission scenarios using PRECIS. Spatial variations of annual mean temperature, mean diurnal range, and temperature seasonality are generated. Furthermore, heat waves defined based on the exceedance of local climatology and their temporal and spatial characteristics are analyzed. The results indicate that the highest temperature and the most intensive heat waves are most likely to occur at the Toronto-Windsor corridor in Southern Ontario. The Northern Ontario, in spite of the relatively low projected temperature, would be under the risk of long-lasting heat waves, and thus needs effective measures to enhance its climate resilience in the future. This study can assist the decision makers in better understanding the future temperature changes in Ontario and provide decision support for mitigating heat-related loss.

  20. Estimation procedure of the efficiency of the heat network segment

    Science.gov (United States)

    Polivoda, F. A.; Sokolovskii, R. I.; Vladimirov, M. A.; Shcherbakov, V. P.; Shatrov, L. A.

    2017-07-01

    An extensive city heat network contains many segments, and each segment operates with different efficiency of heat energy transfer. This work proposes an original technical approach; it involves the evaluation of the energy efficiency function of the heat network segment and interpreting of two hyperbolic functions in the form of the transcendental equation. In point of fact, the problem of the efficiency change of the heat network depending on the ambient temperature was studied. Criteria dependences used for evaluation of the set segment efficiency of the heat network and finding of the parameters for the most optimal control of the heat supply process of the remote users were inferred with the help of the functional analysis methods. Generally, the efficiency function of the heat network segment is interpreted by the multidimensional surface, which allows illustrating it graphically. It was shown that the solution of the inverse problem is possible as well. Required consumption of the heating agent and its temperature may be found by the set segment efficient and ambient temperature; requirements to heat insulation and pipe diameters may be formulated as well. Calculation results were received in a strict analytical form, which allows investigating the found functional dependences for availability of the extremums (maximums) under the set external parameters. A conclusion was made that it is expedient to apply this calculation procedure in two practically important cases: for the already made (built) network, when the change of the heat agent consumption and temperatures in the pipe is only possible, and for the projecting (under construction) network, when introduction of changes into the material parameters of the network is possible. This procedure allows clarifying diameter and length of the pipes, types of insulation, etc. Length of the pipes may be considered as the independent parameter for calculations; optimization of this parameter is made in

  1. ALFVÉNIC WAVE HEATING OF THE UPPER CHROMOSPHERE IN FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Reep, J. W. [National Research Council Post-Doc Program, Naval Research Laboratory, Washington, DC 20375 (United States); Russell, A. J. B., E-mail: jeffrey.reep.ctr@nrl.navy.mil, E-mail: arussell@maths.dundee.ac.uk [Division of Mathematics, University of Dundee, Nethergate, Dundee, DD1 4HN (United Kingdom)

    2016-02-10

    We have developed a numerical model of flare heating due to the dissipation of Alfvénic waves propagating from the corona to the chromosphere. With this model, we present an investigation of the key parameters of these waves on the energy transport, heating, and subsequent dynamics. For sufficiently high frequencies and perpendicular wave numbers, the waves dissipate significantly in the upper chromosphere, strongly heating it to flare temperatures. This heating can then drive strong chromospheric evaporation, bringing hot and dense plasma to the corona. We therefore find three important conclusions: (1) Alfvénic waves, propagating from the corona to the chromosphere, are capable of heating the upper chromosphere and the corona, (2) the atmospheric response to heating due to the dissipation of Alfvénic waves can be strikingly similar to heating by an electron beam, and (3) this heating can produce explosive evaporation.

  2. Development and Testing of a Refractory Millimeter-Wave Absorbent Heat Exchanger

    Science.gov (United States)

    Lambot, Thomas; Myrabo, Leik; Murakami, David; Parkin, Kevin

    2014-01-01

    Central to the Millimeter-Wave Thermal Launch System (MTLS) is the millimeter-wave absorbent heat exchanger. We have developed metallic and ceramic variants, with the key challenge being the millimeter-wave absorbent coatings for each. The ceramic heat exchanger came to fruition first, demonstrating for the first time 1800 K peak surface temperatures under illumination by a 110 GHz Gaussian beam. Absorption efficiencies of up to 80 are calculated for mullite heat exchanger tubes and up to 50 are calculated for alumina tubes. These are compared with estimates based on stratified layer and finite element analyses. The problem of how to connect the 1800 K end of the ceramic tubes to a graphite outlet manifold and nozzle is solved by press fitting, or by threading the ends of the ceramic tubes and screwing them into place. The problem of how to connect the ceramic tubes to a metallic or nylon inlet pipe is solved by using soft compliant PTFE and PVC tubes that accommodate thermal deformations of the ceramic tubes during startup and operation. We show the resulting heat exchangers in static tests using argon and helium as propellants.

  3. Calculations of Temperature, Conductive Heat Flux, and Heat Wave Velocities Due to Radiant Heating of Opaque Materials

    Science.gov (United States)

    2011-11-01

    presentation and the help of Dr. Anthony Kotlar with the Mathcad calculations are greatly appreciated. vi INTENTIONALLY LEFT BLANK. 1 1. Introduction...Corporation. Mathcad 2001; Needham, MA, 2001. 4. Joseph, D. D.; Preziosi, L. Heat Waves. Rev. Modern Physics 1989, 61 (1), 41–73. 5. Cao, B-Y; Guo, Z-Y

  4. Energy Efficiency for Heating, Ventilating, Air-Conditioning Instructors.

    Science.gov (United States)

    Scharmann, Larry, Ed.; Lay, Gary, Ed.

    Intended primarily but not solely for use at the postsecondary level, this curriculum guide contains five units on energy efficiency that were designed to be incorporated into an existing program in heating, ventilating, and air-conditioning. The following topics are examined: how energy conservation pays, heating, ventilation, air-conditioning,…

  5. How Efficient is a Laboratory Burner in Heating Water?

    Science.gov (United States)

    Jansen, Michael P.

    1997-01-01

    Describes an experiment in which chemistry students determine the efficiency of a laboratory burner used to heat water. The reaction is assumed to be the complete combustion of methane, CH4. The experiment is appropriate for secondary school chemistry students familiar with heats of reaction and simple calorimetry. Contains pre-laboratory and…

  6. Attribution and mitigation of heat wave-induced urban heat storage change

    Science.gov (United States)

    Sun, Ting; Kotthaus, Simone; Li, Dan; Ward, H. C.; Gao, Zhiqiu; Ni, Guang-Heng; Grimmond, C. S. B.

    2017-11-01

    When the urban heat island (UHI) effect coincides with a heat wave (HW), thermal stress in cities is exacerbated. Understanding the surface energy balance (SEB) responses to HWs is critical for improving predictions of the synergies between UHIs and HWs. This study evaluates observed SEB characteristics in four cities (Beijing, Łódź, London and Swindon), along with their ambient meteorological conditions, for both HW and background summer climate scenarios. Using the Analytical Objective Hysteresis Model (AnOHM), particular emphasis is on the heat storage. The results demonstrate that in London and Swindon the amount of daytime heat storage and its fraction relative to the net all-wave radiation increase under HWs. Results further demonstrate that such increases are strongly tied to lower wind speeds. The effects of different UHI mitigation measures on heat storage are assessed using AnOHM. Results reveal that use of reflective materials and maintaining higher soil moisture availability can offset the adverse effects of increased heat storage.

  7. Assessment of thermal efficiency of heat recovery coke making

    Science.gov (United States)

    Tiwari, H. P.; Saxena, V. K.; Haldar, S. K.; Sriramoju, S. K.

    2017-08-01

    The heat recovery stamp charge coke making process is quite complicated due to the evolved volatile matter during coking, is partially combusted in oven crown and sole flue in a controlled manner to provide heat for producing metallurgical coke. Therefore, the control and efficient utilization of heat in the oven crown, and sole flue is difficult, which directly affects the operational efficiency. Considering the complexity and importance of thermal efficiency, evolution of different gases, combustion of gasses in oven crown and sole flue, and heating process of coke oven has been studied. A nonlinear regression methodology was used to predict temperature profile of different depth of coal cake during the coking. It was observed that the predicted temperature profile is in good agreement with the actual temperature profile (R2 = 0.98) and is validated with the actual temperature profile of other ovens. A complete study is being done to calculate the material balance, heat balance, and heat losses. This gives an overall understanding of heat flow which affects the heat penetration into the coal cake. The study confirms that 60% heat was utilized during coking.

  8. The solar ultraviolet heating efficiency of the midlatitude thermosphere

    Science.gov (United States)

    Torr, M. R.; Torr, D. G.; Richards, P. G.

    1980-01-01

    In this paper we quantify the major channels by which solar UV energy is transferred to the atmosphere, and determine the UV heating efficiency for the thermosphere. Current knowledge of the solar ultraviolet fluxes, thermospheric chemistry and neutral atmosphere is used in a steady state, interhemispheric solution of the ionospheric continuity, momentum and energy equations. The heating efficiency is found to be a strong function of altitude, and peaks near the altitude of maximum EUV deposition at a value of approximately 50%.

  9. ENERGY EFFICIENCY OF DIFFERENT WAYS OF CENTRAL HEATING

    Directory of Open Access Journals (Sweden)

    A. E. Piir

    2015-01-01

    Full Text Available  The article shows the calculation comparison of fuel for producing of heat-line water with a help of different technological installations, transforming (converting high-grade heat from burning process of fuel or in the process of non-reversible heat exchange with coolant (heating agent, or with a help of heat engines, which allow to decrease losses of working efficiency and thus to reduce the use of fuel. There were considered five types of plants beginning from the  simplest  one  up  to  the  most  complex  in  two  variants,  when  the  heat  exchangers and machines are perfect (ideal and when equipment has the known degree of efficiency (perfection:1 water-heat boiler station, working on organic fuel;2 electrical boiler station, obtaining energy on power transmission lines from condensing power station;3 line heater of TPP, obtaining steam from heating turbine;4 line heater CPP, powered by steam from pressure reducing unit;5 heat pump, producing energy on power supply lines from TPP.In this article were investigated three ideal reversible ways of transformation of   high- grade heat into low-grade heat with a help of decreasing and increasing and combined (suggested by the authors heat transformers and their thermodynamic equivalence was shown in this article. And there were suggested universal installation for electric energy generation, cold and heat of two grades for heat-water supply and the heating process on the base of gascompressors   gas turbines. These results are so important (actual for power engineers of the countries with  increasing consumption  of organic  fuel and  its enhancement in  value and realizing programs of energy saving .The analysis shows, that the quality of produced low-grade heat per unit of used high-grade heat for ideal plants (installations is: electrical boiler unit – 0.7;  water boiler unit – 1.0; for heat pump, heating turbine, combined heat transformers   – 4

  10. Could aerosol emissions be used for regional heat wave mitigation?

    Science.gov (United States)

    Bernstein, D. N.; Neelin, J. D.; Li, Q. B.; Chen, D.

    2013-07-01

    Geoengineering applications by injection of sulfate aerosols into the stratosphere are under consideration as a measure of last resort to counter global warming. Here a potential regional-scale application to offset the impacts of heat waves is critically examined. Using the Weather Research and Forecasting model with fully coupled chemistry (WRF-Chem), the effect of regional-scale sulfate aerosol emission over California in each of two days of the July 2006 heat wave is used to quantify potential reductions in surface temperature as a function of emission rates in a layer at 12 km altitude. Local meteorological factors yield geographical differences in surface air temperature sensitivity. For emission rates of approximately 30 μg m-2 s-1 of sulfate aerosols (with standard WRF-Chem size distribution) over the region, temperature decreases of around 7 °C result during the middle part of the day over the Central Valley, one of the areas hardest hit by the heat wave. Regions more ventilated with oceanic air such as Los Angeles have slightly smaller reductions. The length of the hottest part of the day is also reduced. Advection effects on the aerosol cloud must be more carefully forecast for smaller injection regions. Verification of the impacts could be done via measurements of differences in reflected and surface downward shortwave. Such regional geoengineering applications with specific near-term target effects but smaller cost and side effects could potentially provide a means of testing larger scale applications. However, design considerations for regional applications, such as a preference for injection at a level of relatively low wind speed, differ from those for global applications. The size of the required injections and the necessity of injection close to the target region raise substantial concerns. The evaluation of this regional-scale application is thus consistent with global model evaluations, emphasizing that mitigation via reduction of fossil fuels

  11. Could aerosol emissions be used for regional heat wave mitigation?

    Directory of Open Access Journals (Sweden)

    D. N. Bernstein

    2013-07-01

    Full Text Available Geoengineering applications by injection of sulfate aerosols into the stratosphere are under consideration as a measure of last resort to counter global warming. Here a potential regional-scale application to offset the impacts of heat waves is critically examined. Using the Weather Research and Forecasting model with fully coupled chemistry (WRF-Chem, the effect of regional-scale sulfate aerosol emission over California in each of two days of the July 2006 heat wave is used to quantify potential reductions in surface temperature as a function of emission rates in a layer at 12 km altitude. Local meteorological factors yield geographical differences in surface air temperature sensitivity. For emission rates of approximately 30 μg m−2 s−1 of sulfate aerosols (with standard WRF-Chem size distribution over the region, temperature decreases of around 7 °C result during the middle part of the day over the Central Valley, one of the areas hardest hit by the heat wave. Regions more ventilated with oceanic air such as Los Angeles have slightly smaller reductions. The length of the hottest part of the day is also reduced. Advection effects on the aerosol cloud must be more carefully forecast for smaller injection regions. Verification of the impacts could be done via measurements of differences in reflected and surface downward shortwave. Such regional geoengineering applications with specific near-term target effects but smaller cost and side effects could potentially provide a means of testing larger scale applications. However, design considerations for regional applications, such as a preference for injection at a level of relatively low wind speed, differ from those for global applications. The size of the required injections and the necessity of injection close to the target region raise substantial concerns. The evaluation of this regional-scale application is thus consistent with global model evaluations, emphasizing that mitigation via

  12. Impact of Cold Waves and Heat Waves on the Energy Production Sector

    Directory of Open Access Journals (Sweden)

    Juan A. Añel

    2017-10-01

    Full Text Available Cold and heat waves represent a significant problem for the electricity generation sector. The disruptions cold and heat waves can cause in power production are beyond their consumption impacts through, for instance, higher peak demand. Unexpected stops at thermal or nuclear power plants by excessively high-temperature water constitute clear examples of this. In this invited paper, we use past case studies to analyze the impact of these kinds of events on power production. Subsequently we discuss how events of this nature may evolve over the future in view of their association to climate change. Although the review is not exhaustive, we do expose some ideas that may be relevant for decision making in this area

  13. Projected heat wave characteristics over the Korean Peninsula during the twenty-first century

    Science.gov (United States)

    Shin, Jongsoo; Olson, Roman; An, Soon-Il

    2017-12-01

    Climate change is expected to increase temperatures globally, and consequently more frequent, longer, and hotter heat waves are likely to occur. Ambiguity in defining heat waves appropriately makes it difficult to compare changes in heat wave events over time. This study provides a quantitative definition of a heat wave and makes probabilistic heat wave projections for the Korean Peninsula under two global warming scenarios. Changes to heat waves under global warming are investigated using the representative concentration pathway 4.5 (RCP4.5) and 8.5 (RCP8.5) experiments from 30 coupled models participating in phase five of the Coupled Model Inter-comparison Project. Probabilistic climate projections from multi-model ensembles have been constructed using both simple and weighted averaging. Results from both methods are similar and show that heat waves will be more intense, frequent, and longer lasting. These trends are more apparent under the RCP8.5 scenario as compared to the RCP4.5 scenario. Under the RCP8.5 scenario, typical heat waves are projected to become stronger than any heat wave experienced in the recent measurement record. Furthermore, under this scenario, it cannot be ruled out that Korea will experience heat wave conditions spanning almost an entire summer before the end of the 21st century.

  14. [Impact of heat waves on non-accidental deaths in Jinan, China].

    Science.gov (United States)

    Zhang, J; Liu, S Q; Zhou, L; Gong, S P; Liu, Y L; Zhang, Y; Zhang, J

    2016-02-20

    To assess the impact of heat waves on non-accidental deaths, and to investigate the influencing factors for deaths caused by heat waves in Jinan, China. Daily death data and meteorological data for summer days with or without heat waves in Jinan from 2012 to 2014 were collected, and a cross-over analysis was conducted to evaluate the influence of heat waves on non-accidental deaths and deaths caused by other reasons. The univariate and multivariate logistic regression models were used to investigate the influencing factors for deaths caused by heat waves. The risks of non-accidental deaths and deaths caused by circulation system diseases during the days with heat waves were 1.82 times(95% CI: 1.47~2.36) and 1.53 times(95% CI: 1.14~2.07) those during the days without heat waves. The multivariate logistic regression analysis showed that old age(≥75 years)(OR=1.184, 95% CI: 1.068~1.313), low educational level(OR=1.187, 95% CI: 1.064~1.324), and deaths outside hospital(OR=1.105, 95% CI: 1.009~1.210) were associated with the high risk of deaths during the days with heat waves. Heat waves significantly increase the risk of non-accidental deaths and deaths caused by circulation system diseases in Jinan, and the deaths during the days with heat waves are related to age, educational level, and place of death.

  15. Exergetic efficiency optimization for an irreversible heat pump ...

    Indian Academy of Sciences (India)

    temperature heat reservoirs by taking exergetic efficiency as the optimization objective combining exergy concept with finite-time thermodynamics (FTT). Exergetic efficiency is defined as the ratio of rate of exergy output to rate of exergy input of the system ...

  16. Effects of Simulated Heat Waves on Cardiovascular Functions in Senile Mice

    Directory of Open Access Journals (Sweden)

    Xiakun Zhang

    2014-08-01

    Full Text Available The mechanism of the effects of simulated heat waves on cardiovascular disease in senile mice was investigated. Heat waves were simulated in a TEM1880 meteorological environment simulation chamber, according to a heat wave that occurred in July 2001 in Nanjing, China. Eighteen senile mice were divided into control, heat wave, and heat wave BH4 groups, respectively. Mice in the heat wave and heat wave BH4 groups were exposed to simulated heat waves in the simulation chamber. The levels of ET-1, NO, HSP60, SOD, TNF, sICAM-1, and HIF-1α in each group of mice were measured after heat wave simulation. Results show that heat waves decreased SOD activity in the myocardial tissue of senile mice, increased NO, HSP60, TNF, sICAM-1, and HIF-1α levels, and slightly decreased ET-1 levels, BH4 can relieve the effects of heat waves on various biological indicators. After a comprehensive analysis of the experiments above, we draw the followings conclusions regarding the influence of heat waves on senile mice: excess HSP60 activated immune cells, and induced endothelial cells and macrophages to secrete large amounts of ICAM-1, TNF-α, and other inflammatory cytokines, it also activated the inflammation response in the body and damaged the coronary endothelial cell structure, which increased the permeability of blood vessel intima and decreased SOD activity in cardiac tissues. The oxidation of lipoproteins in the blood increased, and large amounts of cholesterol were generated. Cholesterol penetrated the intima and deposited on the blood vessel wall, forming atherosclerosis and leading to the occurrence of cardiovascular disease in senile mice. These results maybe are useful for studying the effects of heat waves on elderly humans, which we discussed in the discussion chapter.

  17. Heat waves and cause-specific mortality at all ages.

    Science.gov (United States)

    Basagaña, Xavier; Sartini, Claudio; Barrera-Gómez, Jose; Dadvand, Payam; Cunillera, Jordi; Ostro, Bart; Sunyer, Jordi; Medina-Ramón, Mercedes

    2011-11-01

    Mortality has been shown to increase with extremely hot ambient temperatures. Details on the specific cause of mortality can be useful for improving preventive policies. Infants are often identified as a population that is vulnerable to extreme heat conditions; however, information on heat and infant mortality is scarce, with no studies reporting on cause-specific mortality. The study includes all deaths in the Catalonia region of Spain during the warm seasons of 1983-2006 (503,389 deaths). We used the case-crossover design to evaluate the association between the occurrence of extremely hot days (days with maximum temperature above the 95th percentile) and mortality. Total mortality and infant mortality were stratified into 66 and 8 causes of death, respectively. Three consecutive hot days increased total daily mortality by 19%. We calculated that 1.6% of all deaths were attributable to heat. About 40% of attributable deaths did not occur during heat-wave periods. The causes of death that were increased included cardiovascular and respiratory diseases, mental and nervous system disorders, infectious and digestive system diseases, diabetes, and some external causes such as suicide. In infants, the effect of heat was observed on the same day and was detected only for conditions originating in the perinatal period (relative risk = 1.53 [95% confidence interval = 1.16-2.02]). Within the perinatal causes, cardiovascular, respiratory, digestive system, and hemorrhagic and hematologic disorders were the causes of death with stronger effects. Heat contributes to an increase in mortality from several causes. In infants, the first week of life is the most critical window of vulnerability.

  18. A criterion to maximize the irreversible efficiency in heat engines

    CERN Document Server

    Aragon-Gonzalez, G; Leon-Galicia, A; Musharrafie-Martinez, M

    2003-01-01

    The purpose of this work is to obtain a more precise calculation of the effective limits to the efficiency, of several cyclic heat engines. This calculation is based, first, on the equations describing the irreversible efficiency, and second, on a method which results from a general criterion to maximize this efficiency, applicable to several heat engines. With this method, we apply the criterion to maximize efficiencies; establish lower and upper bounds, corresponding to the efficiencies of Curzon-Ahlborn-like and Carnot-like heat engines; and, finally, find analytical or numerical expressions for the efficiencies eta sub m sub e and eta sub m sub a sub x. eta sub m sub a sub x is the maximum irreversible efficiency; eta sub m sub e is the efficiency in which the irreversible efficiency achieves its maximum, in a similar way to the Curzon-Ahlborn efficiency (maximum work or power). The method was applied to a Brayton cycle, presenting internal dissipations of the working fluid and irreversibilities due to th...

  19. Efficient wave-function matching approach for quantum transport calculations

    DEFF Research Database (Denmark)

    Sørensen, Hans Henrik Brandenborg; Hansen, Per Christian; Petersen, Dan Erik

    2009-01-01

    The wave-function matching (WFM) technique has recently been developed for the calculation of electronic transport in quantum two-probe systems. In terms of efficiency it is comparable to the widely used Green's function approach. The WFM formalism presented so far requires the evaluation of all ...

  20. Sahelian springtime heat waves and their evolution over the past 60 years

    Science.gov (United States)

    Barbier, Jessica; Guichard, Françoise; Bouniol, Dominique; Couvreux, Fleur; Roehrig, Romain

    2017-04-01

    The Sahel is a semi-arid region which experiences very high temperature both during day- and night-times: monthly-mean temperatures in Spring typically oscillate between 30 and 40°C. At the same time a strong climatic warming has been observed over the past 60 years in this region: it reaches +1,5°C over April-May. Thus heat waves in this region have severe impacts on health, ecosystem, agriculture and more broadly economical activities, which will probably worsen in the context of climate change. However, heat waves in the Sahel remain poorly studied. The present work documents Sahelian heat waves and assesses their evolution across the last 60 years. Properties of heat waves are sensitive to the way they are detected. Here, we use a methodology based on anomalies that allows to filter the seasonal, inter-annual and climatic evolutions, using a percentile-type threshold. It is applied separately to daily maximum and minimum temperatures and leads to two types of heat waves: day- and night-time ones. This separation matters because physical processes linked to minimum and maximum temperatures can be quite distinct. The changes in both types of heat wave were studied over the period 1950-2012 using the Berkeley Earth Surface Temperature gridded product: several heat wave characteristics were investigated, including morphological ones such as the length and the spatial extent of the event, the heat wave intensity and the associated warming trends. We found no significant trends in the frequency, duration and spatial extent of both types of heat waves, while on the other hand their maximum and minimum temperatures displayed significant positive trends. They were mainly explained by the regional warming. By contrast, with a standard climatic heat index using percentile-threshold on raw temperatures, both day- and night-time heat wave frequencies were increasing, and while the day-time heat waves were getting longer and larger, the night-time heat waves were getting

  1. Efficiency improvements by geothermal heat integration in a lignocellulosic biorefinery.

    Science.gov (United States)

    Sohel, M Imroz; Jack, Michael

    2010-12-01

    In an integrated geothermal biorefinery, low-grade geothermal heat is used as process heat to allow the co-products of biofuel production to become available for higher-value uses. In this paper we consider integrating geothermal heat into a biochemical lignocellulosic biorefinery so that the lignin-enriched residue can be used either as a feedstock for chemicals and materials or for on-site electricity generation. Depending on the relative economic value of these two uses, we can maximize revenue of a biorefinery by judicious distribution of the lignin-enriched residue between these two options. We quantify the performance improvement from integrating geothermal energy for an optimized system. We then use a thermodynamic argument to show that integrating geothermal heat into a biorefinery represents an improvement in overall resource utilization efficiency in all cases considered. Finally, possible future technologies for electricity generation are considered which could improve this efficiency further. 2010 Elsevier Ltd. All rights reserved.

  2. Time-series Analysis of Heat Waves and Emergency Department Visits in Atlanta, 1993 to 2012.

    Science.gov (United States)

    Chen, Tianqi; Sarnat, Stefanie E; Grundstein, Andrew J; Winquist, Andrea; Chang, Howard H

    2017-05-31

    Heat waves are extreme weather events that have been associated with adverse health outcomes. However, there is limited knowledge of heat waves' impact on population morbidity, such as emergency department (ED) visits. We investigated associations between heat waves and ED visits for 17 outcomes in Atlanta over a 20-year period, 1993-2012. Associations were estimated using Poisson log-linear models controlling for continuous air temperature, dew-point temperature, day of week, holidays, and time trends. We defined heat waves as periods of consecutive days with temperatures beyond the 98th percentile of the temperature distribution over the period from 1945-2012. We considered six heat wave definitions using maximum, minimum, and average air temperatures and apparent temperatures. Associations by heat wave characteristics were examined. Among all outcome-heat wave combinations, associations were strongest between ED visits for acute renal failure and heat waves defined by maximum apparent temperature at lag 0 [relative risk (RR) = 1.15; 95% confidence interval (CI): 1.03-1.29], ED visits for ischemic stroke and heat waves defined by minimum temperature at lag 0 (RR = 1.09; 95% CI: 1.02-1.17), and ED visits for intestinal infection and heat waves defined by average temperature at lag 1 (RR = 1.10; 95% CI: 1.00-1.21). ED visits for all internal causes were associated with heat waves defined by maximum temperature at lag 1 (RR = 1.02; 95% CI: 1.00, 1.04). Heat waves can confer additional risks of ED visits beyond those of daily air temperature, even in a region with high air-conditioning prevalence. https://doi.org/10.1289/EHP44.

  3. The influence of heat sink temperature on the seasonal efficiency of shallow geothermal heat pumps

    Science.gov (United States)

    Pełka, Grzegorz; Luboń, Wojciech; Sowiżdżał, Anna; Malik, Daniel

    2017-11-01

    Geothermal heat pumps, also known as ground source heat pumps (GSHP), are the most efficient heating and cooling technology utilized nowadays. In the AGH-UST Educational and Research Laboratory of Renewable Energy Sources and Energy Saving in Miękinia, shallow geothermal heat is utilized for heating. In the article, the seasonal efficiency of two geothermal heat pump systems are described during the 2014/2015 heating season, defined as the period between 1st October 2014 and 30th April 2015. The first system has 10.9 kW heating capacity (according to European Standard EN 14511 B0W35) and extracts heat from three vertical geothermal loops at a depth of 80m each. During the heating season, tests warmed up the buffer to 40°C. The second system has a 17.03 kW heating capacity and extracts heat from three vertical geothermal loops at a depth of 100 m each, and the temperature of the buffer was 50°C. During the entire heating season, the water temperatures of the buffers was constant. Seasonal performance factors were calculated, defined as the quotient of heat delivered by a heat pump to the system and the sum of electricity consumed by the compressor, source pump, sink pump and controller of heat pumps. The measurements and calculations give the following results: - The first system was supplied with 13 857 kWh/a of heat and consumed 3 388 kWh/a electricity. The SPF was 4.09 and the average temperature of outlet water from heat pump was 40.8°C, and the average temperature of brine flows into the evaporator was 3.7 °C; - The second system was supplied with 12 545 kWh/a of heat and consumed 3 874 kWh/a electricity. The SPF was 3.24 and the average temperature of outlet water from heat pump was 51.6°C, and the average temperature of brine flows into the evaporator was 5.3°C. To summarize, the data shown above presents the real SPF of the two systems. It will be significant in helping to predict the SPF of objects which will be equipped with ground source heat pumps.

  4. Efficient excitation and detection of standing spin wave in Permalloy film: Demonstration of spin wave resonator

    Science.gov (United States)

    Kiseki, K.; Yakata, S.; Kimura, T.

    2012-11-01

    A magnetic resonator consisting of periodical nonmagnetic electrodes on a ferromagnetic metallic film has been fabricated. We demonstrated that the resonator efficiently excites the standing magneto-static surface spin wave with the specific wavelength, which can be controlled by the interval of the periodical electrode. The operation frequency over 5 GHz was confirmed at the interval of 4 μm under a small bias magnetic field less than 100 Oe. The optimization of the electrode pattern for the efficient detection of the standing spin wave was also demonstrated.

  5. Thermal bioclimate in Strasbourg - the 2003 heat wave

    Science.gov (United States)

    Matzarakis, Andreas; de Rocco, Manuela; Najjar, Georges

    2009-10-01

    This case study highlights the implications of the 2003 heat wave for the city of Strasbourg, France. The urban centers of France and other European countries were particularly affected by the heat wave. In some urban areas, the mortality rate was 60% above the expected value (Institute de Veille Sanitaire, 2003). The 2003 heat wave demonstrated once again that populations in urban centers are much more affected by extreme meteorological events than people living in rural areas. The aim of this analysis is to explore differences in thermal comfort conditions of (a) the city center of Strasbourg, and (b) its hinterland. The differences in thermal conditions existing between rural and urban areas are quantified by using a bio-climatological index termed physiologically equivalent temperature (PET). This index is based on the human energy balance and builds a relevant index for the quantification of the thermal environment of humans. We calculate the PET for the years 2003 and 2004 to highlight the temporal changes in the severity of climate extremes. The spatial scope of this study is improved compared to previous works in the field through the inclusion of PET calculations for five different sites on a central place in Strasbourg (Place Kléber). The calculations are characterized by different sky view factors and are compared to the reference site, which is located in a rural area. In the rural hinterland (Entzheim), the analysis of PET indicates a strong cold thermal stress during the winter months but no significant stress in summer. In 2003, summer temperatures were sensed as warmer compared to other years, but did not reach the extreme temperatures that may cause severe heat stress. For both the rural and the urban study sites PET was higher in the summer of 2003 than in 2004, which reflects the inferior thermal conditions in the urban area during the heat wave in 2003. For the entire study period, urban and rural day-time PET reached similar maximal values

  6. A heat wave and dispersal cause dominance shift and decrease biomass in experimental metacommunities

    NARCIS (Netherlands)

    Eggers, Sarah Lena; Eriksson, Britas Klemens; Matthiessen, Birte

    In experimental metacommunities with marine benthic microalgae, we tested whether heat stress changes effects of connectivity and habitat heterogeneity on metacommunity structure and functioning, by manipulating a simulated heat wave, dispersal frequency and a light intensity gradient. We found that

  7. The impact of heat waves on mortality in 9 European cities: results from the EuroHEAT project

    Directory of Open Access Journals (Sweden)

    Bisanti Luigi

    2010-07-01

    Full Text Available Abstract Background The present study aimed at developing a standardized heat wave definition to estimate and compare the impact on mortality by gender, age and death causes in Europe during summers 1990-2004 and 2003, separately, accounting for heat wave duration and intensity. Methods Heat waves were defined considering both maximum apparent temperature and minimum temperature and classified by intensity, duration and timing during summer. The effect was estimated as percent increase in daily mortality during heat wave days compared to non heat wave days in people over 65 years. City specific and pooled estimates by gender, age and cause of death were calculated. Results The effect of heat waves showed great geographical heterogeneity among cities. Considering all years, except 2003, the increase in mortality during heat wave days ranged from + 7.6% in Munich to + 33.6% in Milan. The increase was up to 3-times greater during episodes of long duration and high intensity. Pooled results showed a greater impact in Mediterranean (+ 21.8% for total mortality than in North Continental (+ 12.4% cities. The highest effect was observed for respiratory diseases and among women aged 75-84 years. In 2003 the highest impact was observed in cities where heat wave episode was characterized by unusual meteorological conditions. Conclusions Climate change scenarios indicate that extreme events are expected to increase in the future even in regions where heat waves are not frequent. Considering our results prevention programs should specifically target the elderly, women and those suffering from chronic respiratory disorders, thus reducing the impact on mortality.

  8. Heat waves and morbidity: current knowledge and further direction-a comprehensive literature review.

    Science.gov (United States)

    Li, Mengmeng; Gu, Shaohua; Bi, Peng; Yang, Jun; Liu, Qiyong

    2015-05-18

    In the past few decades, several devastating heat wave events have significantly challenged public health. As these events are projected to increase in both severity and frequency in the future, it is important to assess the relationship between heat waves and the health indicators that can be used in the early warning systems to guide the public health response. Yet there is a knowledge gap in the impact of heat waves on morbidity. In this study, a comprehensive review was conducted to assess the relationship between heat waves and different morbidity indicators, and to identify the vulnerable populations. The PubMed and ScienceDirect database were used to retrieve published literature in English from 1985 to 2014 on the relationship between heat waves and morbidity, and the following MeSH terms and keywords were used: heat wave, heat wave, morbidity, hospital admission, hospitalization, emergency call, emergency medical services, and outpatient visit. Thirty-three studies were included in the final analysis. Most studies found a short-term negative health impact of heat waves on morbidity. The elderly, children, and males were more vulnerable during heat waves, and the medical care demand increased for those with existing chronic diseases. Some social factors, such as lower socioeconomic status, can contribute to heat-susceptibility. In terms of study methods and heat wave definitions, there remain inconsistencies and uncertainties. Relevant policies and guidelines need to be developed to protect vulnerable populations. Morbidity indicators should be adopted in heat wave early warning systems in order to guide the effective implementation of public health actions.

  9. EFFICIENCY AND LIFETIME OF SOLAR COLLECTORS FOR SOLAR HEATING PLANTS

    DEFF Research Database (Denmark)

    The 12.5 m² flat plate solar collector HT, today marketed by Arcon Solvarme A/S, has been used in solar heating plants in Scandinavia since 1983. The collector is designed to operate in a temperature interval between 40°C and 90°C. The efficiency of the collector has been strongly improved since...... it was introduced on the market. The paper will present the increase of the efficiency of the collector due to technical improvements since 1983. Further, measurements from the spring of 2009 of the efficiency of two HT collectors, which have been in operation in the solar heating plant Ottrupgaard, Skørping......, Denmark since 1994 with a constant high flow rate and in the solar heating plant Marstal, Denmark since 1996 with a variable flow rate, will be presented. The efficiencies will be compared to the efficiencies of the collectors when they were first installed in the solar heating plants. The measurements...

  10. EFFICIENCY AND LIFETIME OF SOLAR COLLECTORS FOR SOLAR HEATING PLANTS

    DEFF Research Database (Denmark)

    Fan, Jianhua; Chen, Ziqian; Furbo, Simon

    2009-01-01

    The 12.5 m² flat plate solar collector HT, today marketed by Arcon Solvarme A/S, has been used in solar heating plants in Scandinavia since 1983. The collector is designed to operate in a temperature interval between 40°C and 90°C. The efficiency of the collector has been strongly improved since...... it was introduced on the market. The paper will present the increase of the efficiency of the collector due to technical improvements since 1983. Further, measurements from the spring of 2009 of the efficiency of two HT collectors, which have been in operation in the solar heating plant Ottrupgaard, Skørping......, Denmark since 1994 with a constant high flow rate and in the solar heating plant Marstal, Denmark since 1996 with a variable flow rate, will be presented. The efficiencies will be compared to the efficiencies of the collectors when they were first installed in the solar heating plants. The measurements...

  11. Size dependence of efficiency at maximum power of heat engine

    KAUST Repository

    Izumida, Y.

    2013-10-01

    We perform a molecular dynamics computer simulation of a heat engine model to study how the engine size difference affects its performance. Upon tactically increasing the size of the model anisotropically, we determine that there exists an optimum size at which the model attains the maximum power for the shortest working period. This optimum size locates between the ballistic heat transport region and the diffusive heat transport one. We also study the size dependence of the efficiency at the maximum power. Interestingly, we find that the efficiency at the maximum power around the optimum size attains a value that has been proposed as a universal upper bound, and it even begins to exceed the bound as the size further increases. We explain this behavior of the efficiency at maximum power by using a linear response theory for the heat engine operating under a finite working period, which naturally extends the low-dissipation Carnot cycle model [M. Esposito, R. Kawai, K. Lindenberg, C. Van den Broeck, Phys. Rev. Lett. 105, 150603 (2010)]. The theory also shows that the efficiency at the maximum power under an extreme condition may reach the Carnot efficiency in principle.© EDP Sciences Società Italiana di Fisica Springer-Verlag 2013.

  12. Forest response to heat waves at the dry timberline

    Science.gov (United States)

    Yakir, D.; Rotenberg, E.; Tatrinov, F.; Ogee, J.; Maseyk, K.

    2012-04-01

    Predictions of climate change consistently indicate continuous warming and drying for the entire Mediterranean basin and other regions during the next century. Investigating forest functioning at the current dry and hot "timberline" has therefore implications for predicting future forest distribution. In such investigations we should consider the forest adjustments to extreme conditions both at the long-term average climate basis, as at the time-scale of episodic extreme events, such as heat waves and droughts. Investigating both aspects in a 45-yr old semi-arid pine forest at the dry timberline (MuSICA) was used to test our understandings of underlying processes, and our ability to account for such differential responses.

  13. Single ion heat engine with maximum efficiency at maximum power

    OpenAIRE

    Abah, Obinna; Rossnagel, Johannes; Jacob, Georg; Deffner, Sebastian; Schmidt-Kaler, Ferdinand; Singer, Kilian; Lutz, Eric

    2012-01-01

    We propose an experimental scheme to realize a nano heat engine with a single ion. An Otto cycle may be implemented by confining the ion in a linear Paul trap with tapered geometry and coupling it to engineered laser reservoirs. The quantum efficiency at maximum power is analytically determined in various regimes. Moreover, Monte Carlo simulations of the engine are performed that demonstrate its feasibility and its ability to operate at maximum efficiency of 30% under realistic conditions.

  14. MAGNETOHYDRODYNAMIC WAVES AND CORONAL HEATING: UNIFYING EMPIRICAL AND MHD TURBULENCE MODELS

    Energy Technology Data Exchange (ETDEWEB)

    Sokolov, Igor V.; Van der Holst, Bart; Oran, Rona; Jin, Meng; Manchester, Ward B. IV; Gombosi, Tamas I. [Department of AOSS, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109 (United States); Downs, Cooper [Predictive Science Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121 (United States); Roussev, Ilia I. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Evans, Rebekah M., E-mail: igorsok@umich.edu [NASA Goddard Space Flight Center, Space Weather Lab, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States)

    2013-02-10

    We present a new global model of the solar corona, including the low corona, the transition region, and the top of the chromosphere. The realistic three-dimensional magnetic field is simulated using the data from the photospheric magnetic field measurements. The distinctive feature of the new model is incorporating MHD Alfven wave turbulence. We assume this turbulence and its nonlinear dissipation to be the only momentum and energy source for heating the coronal plasma and driving the solar wind. The difference between the turbulence dissipation efficiency in coronal holes and that in closed field regions is because the nonlinear cascade rate degrades in strongly anisotropic (imbalanced) turbulence in coronal holes (no inward propagating wave), thus resulting in colder coronal holes, from which the fast solar wind originates. The detailed presentation of the theoretical model is illustrated with the synthetic images for multi-wavelength EUV emission compared with the observations from SDO AIA and STEREO EUVI instruments for the Carrington rotation 2107.

  15. Excitation of kinetic Alfven waves by resonant mode conversion and longitudinal heating of magnetized plasmas

    Science.gov (United States)

    Tanaka, Motohiko; Sato, Tetsuya; Hasegawa, A.

    1989-01-01

    The excitation of the kinetic Alfven wave by resonant mode conversion and longitudinal heating of the plasma by the kinetic Alfven wave were demonstrated on the basis of a macroscale particle simulation. The longitudinal electron current was shown to be cancelled by the ions. The kinetic Alfven wave produced an ordered motion of the plasma particles in the wave propagation direction. The electrons were pushed forward along the ambient magnetic field by absorbing the kinetic Alfven wave through the Landau resonance.

  16. maximum conversion efficiency of thermionic heat to electricity ...

    African Journals Online (AJOL)

    DJFLEX

    ELECTRICITY CONVERTERS USING PURE TUNGSTEN AS THE. EMITTER: A THEORETICAL ... In this work, analysis of the efficiency of a thermionic converter of heat to electricity is made in terms of the potential difference between ... leave a conductor experiences a strong force attracting it back towards the conductor ...

  17. Optimal power and efficiency of quantum Stirling heat engines

    Science.gov (United States)

    Yin, Yong; Chen, Lingen; Wu, Feng

    2017-01-01

    A quantum Stirling heat engine model is established in this paper in which imperfect regeneration and heat leakage are considered. A single particle which contained in a one-dimensional infinite potential well is studied, and the system consists of countless replicas. Each particle is confined in its own potential well, whose occupation probabilities can be expressed by the thermal equilibrium Gibbs distributions. Based on the Schrödinger equation, the expressions of power output and efficiency for the engine are obtained. Effects of imperfect regeneration and heat leakage on the optimal performance are discussed. The optimal performance region and the optimal values of important parameters of the engine cycle are obtained. The results obtained can provide some guidelines for the design of a quantum Stirling heat engine.

  18. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers.

    Science.gov (United States)

    Tu, Y D; Wang, R Z; Ge, T S; Zheng, X

    2017-01-12

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump's efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

  19. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

    Science.gov (United States)

    Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

    2017-01-01

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8-3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications.

  20. Comfortable, high-efficiency heat pump with desiccant-coated, water-sorbing heat exchangers

    Science.gov (United States)

    Tu, Y. D.; Wang, R. Z.; Ge, T. S.; Zheng, X.

    2017-01-01

    Comfortable, efficient, and affordable heating, ventilation, and air conditioning systems in buildings are highly desirable due to the demands of energy efficiency and environmental friendliness. Traditional vapor-compression air conditioners exhibit a lower coefficient of performance (COP) (typically 2.8–3.8) owing to the cooling-based dehumidification methods that handle both sensible and latent loads together. Temperature- and humidity-independent control or desiccant systems have been proposed to overcome these challenges; however, the COP of current desiccant systems is quite small and additional heat sources are usually needed. Here, we report on a desiccant-enhanced, direct expansion heat pump based on a water-sorbing heat exchanger with a desiccant coating that exhibits an ultrahigh COP value of more than 7 without sacrificing any comfort or compactness. The pump’s efficiency is doubled compared to that of pumps currently used in conventional room air conditioners, which is a revolutionary HVAC breakthrough. Our proposed water-sorbing heat exchanger can independently handle sensible and latent loads at the same time. The desiccants adsorb moisture almost isothermally and can be regenerated by condensation heat. This new approach opens up the possibility of achieving ultrahigh efficiency for a broad range of temperature- and humidity-control applications. PMID:28079171

  1. Urban warming in the 2013 summer heat wave in eastern China

    Science.gov (United States)

    Wang, Jun; Yan, Zhongwei; Quan, Xiao-Wei; Feng, Jinming

    2017-05-01

    The impact of urban warming during the 2013 July-August extreme heat wave event across the Yangtze River Delta (YRD) in China was assessed. Using a newly developed high-resolution, land-use dataset, urban stations were identified from a total of 101 stations in the YRD. The difference between urban and non-urban/rural stations indicates that urban warming reached 1.22 °C in the 2013 summer heat wave. The new land-use dataset was then input to the Weather Research and Forecasting model to further understand the dynamical/physical processes of the urban warming during the heat wave. The model-simulated urban warming is 1.5 °C. Impacts of urbanization on near-surface temperature had strong diurnal variation, reaching a peak at 19:00 LST, around sunset. In the daytime, urban warming was mainly caused by enhanced sensible heat fluxes and longwave radiation from the surface. Because of reduced latent heat flux and increased heat capacity, urban ground stored much more heat than rural ground during the daytime, which is later released as sensible heat flux from the surface at night, leading to the nocturnal urban warming. The simulation results also suggest a positive feedback between urban warming and heat wave intensity, which makes the heat wave more intense in urban than rural areas and the urban warming during the extreme heat wave stronger than its climatological mean.

  2. 76 FR 62777 - Forum-Trends and Causes of Observed Changes in Heat Waves, Cold Waves, Floods and Drought

    Science.gov (United States)

    2011-10-11

    ... National Oceanic and Atmospheric Administration Forum--Trends and Causes of Observed Changes in Heat Waves, Cold Waves, Floods and Drought AGENCY: National Environmental Satellite, Data, and Information Service....com/a/noaa.gov/heatwaves-coldwaves-floods-drought/ . FOR FURTHER INFORMATION CONTACT: Brooke Stewart...

  3. Efficiency at maximum power of thermally coupled heat engines.

    Science.gov (United States)

    Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph

    2012-04-01

    We study the efficiency at maximum power of two coupled heat engines, using thermoelectric generators (TEGs) as engines. Assuming that the heat and electric charge fluxes in the TEGs are strongly coupled, we simulate numerically the dependence of the behavior of the global system on the electrical load resistance of each generator in order to obtain the working condition that permits maximization of the output power. It turns out that this condition is not unique. We derive a simple analytic expression giving the relation between the electrical load resistance of each generator permitting output power maximization. We then focus on the efficiency at maximum power (EMP) of the whole system to demonstrate that the Curzon-Ahlborn efficiency may not always be recovered: The EMP varies with the specific working conditions of each generator but remains in the range predicted by irreversible thermodynamics theory. We discuss our results in light of nonideal Carnot engine behavior.

  4. Heat waves measured with MODIS land surface temperature data predict changes in avian community structure

    Science.gov (United States)

    Thomas P. Albright; Anna M. Pidgeon; Chadwick D. Rittenhouse; Murray K. Clayton; Curtis H. Flather; Patrick D. Culbert; Volker C. Radeloff

    2011-01-01

    Heat waves are expected to become more frequent and severe as climate changes, with unknown consequences for biodiversity. We sought to identify ecologically-relevant broad-scale indicators of heat waves based on MODIS land surface temperature (LST) and interpolated air temperature data and assess their associations with avian community structure. Specifically, we...

  5. Heat waves according to warm spell duration index in Slovakia during 1901-2016

    Science.gov (United States)

    Bochníček, Oliver; Faško, Pavel; Markovič, Ladislav

    2017-04-01

    A heat wave is a prolonged period of extremely high temperatures for a particular region. However, there exist no universal definitions for a heat wave as it is relative to a specific area and to a certain time of year. In fact, average temperatures in one region may be considered heat wave conditions in another. For instance, an average day in the Mediterranean would be regarded as heat wave conditions in Northern Europe. We have known that World Meteorological Organization definition of a heatwave which is "when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 °C, the normal period being 1961-1990". This rule has been accepted in contribution Heat waves and warm periods in Slovakia (Oliver Bochníček - Pavol Fa\\vsko - Ladislav Markovič) published (presented) in EGU 2016. To move on we have tried another criterion for heat waves evaluation (according to warm spell duration index, WSDI) and period since 1901 (1951) to 2016. Important for many sectors (hydrology, agriculture, transportation and tourism) is, that heat waves have been expected during the whole year and period, that is why it can have various impacts. Heat waves occurrence gave us interesting results especially after the 1990.

  6. The great 2006 heat wave over California and Nevada: Signal of an increasing trend

    Science.gov (United States)

    Gershunov, A.; Cayan, D.R.; Iacobellis, S.F.

    2009-01-01

    Most of the great California-Nevada heat waves can be classified into primarily daytime or nighttime events depending on whether atmospheric conditions are dry or humid. A rash of nighttime-accentuated events in the last decade was punctuated by an unusually intense case in July 2006, which was the largest heat wave on record (1948-2006). Generally, there is a positive trend in heat wave activity over the entire region that is expressed most strongly and clearly in nighttime rather than daytime temperature extremes. This trend in nighttime heat wave activity has intensified markedly since the 1980s and especially since 2000. The two most recent nighttime heat waves were also strongly expressed in extreme daytime temperatures. Circulations associated with great regional heat waves advect hot air into the region. This air can be dry or moist, depending on whether a moisture source is available, causing heat waves to be expressed preferentially during day or night. A remote moisture source centered within a marine region west of Baja California has been increasing in prominence because of gradual sea surface warming and a related increase in atmospheric humidity. Adding to the very strong synoptic dynamics during the 2006 heat wave were a prolonged stream of moisture from this southwestern source and, despite the heightened humidity, an environment in which afternoon convection was suppressed, keeping cloudiness low and daytime temperatures high. The relative contributions of these factors and possible relations to global warming are discussed. ?? 2009 American Meteorological Society.

  7. Heat wave hazard classification and risk assessment using artificial intelligence fuzzy logic.

    Science.gov (United States)

    Keramitsoglou, Iphigenia; Kiranoudis, Chris T; Maiheu, Bino; De Ridder, Koen; Daglis, Ioannis A; Manunta, Paolo; Paganini, Marc

    2013-10-01

    The average summer temperatures as well as the frequency and intensity of hot days and heat waves are expected to increase due to climate change. Motivated by this consequence, we propose a methodology to evaluate the monthly heat wave hazard and risk and its spatial distribution within large cities. A simple urban climate model with assimilated satellite-derived land surface temperature images was used to generate a historic database of urban air temperature fields. Heat wave hazard was then estimated from the analysis of these hourly air temperatures distributed at a 1-km grid over Athens, Greece, by identifying the areas that are more likely to suffer higher temperatures in the case of a heat wave event. Innovation lies in the artificial intelligence fuzzy logic model that was used to classify the heat waves from mild to extreme by taking into consideration their duration, intensity and time of occurrence. The monthly hazard was subsequently estimated as the cumulative effect from the individual heat waves that occurred at each grid cell during a month. Finally, monthly heat wave risk maps were produced integrating geospatial information on the population vulnerability to heat waves calculated from socio-economic variables.

  8. Nonlinear waves in an ultrarelativistic heat-conducting fluid II (Eckart formulation

    Directory of Open Access Journals (Sweden)

    Sebastiano Giambò

    2012-06-01

    Full Text Available In this paper a second-order theory for relativistic heat-conducting fluids is derived in the Eckart scheme, based on the assumption that the entropy 4-current should include quadratic terms in the heat flux. In the special case of ultrarelativistic fluids, the velocities of hydrodynamic and thermal weak discontinuity wave fronts are determined and, through the second-order compatibility conditions, the discontinuities associated to the waves and the transport equations for the amplitude of the discontinuities are found out. Finally, for heat wave, plane, cylindrical and spherical diverging waves are also investigated.

  9. [Selective Heating of Membrane-forming Holes in Teflon Film Exposed to Decimeter Waves].

    Science.gov (United States)

    Alekseev, S I; Fesenko, E E; Fesenko, E E

    2015-01-01

    Calculations of heating of membrane-forming holes in Teflon film exposed to decimeter waves were performed. The dependence of the temperature increment in holes on the geometry of holes, electrolyte concentration, and decimeter wave frequency was studied. The kinetics of heating depending on the hole diameter was also obtained. It was concluded that the observed in the experiment effects of the decimeter wave on bilayer lipid membranes resulted from the elevated concentration of decimeter electromagnetic waves in membrane-forming hole that led to selective heating of electrolyte in hole and bilayer lipid membranes.

  10. Technology Roadmaps: Energy-efficient Buildings: Heating and Cooling Equipment

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Buildings account for almost a third of final energy consumption globally and are an equally important source of CO2 emissions. Currently, both space heating and cooling as well as hot water are estimated to account for roughly half of global energy consumption in buildings. Energy-efficient and low/zero-carbon heating and cooling technologies for buildings have the potential to reduce CO2 emissions by up to 2 gigatonnes (Gt) and save 710 million tonnes oil equivalent (Mtoe) of energy by 2050. Most of these technologies -- which include solar thermal, combined heat and power (CHP), heat pumps and thermal energy storage -- are commercially available today. The Energy-Efficient Buildings: Heating and Cooling Equipment Roadmap sets out a detailed pathway for the evolution and deployment of the key underlying technologies. It finds that urgent action is required if the building stock of the future is to consume less energy and result in lower CO2 emissions. The roadmap concludes with a set of near-term actions that stakeholders will need to take to achieve the roadmap's vision.

  11. On the efficiency of solar heating in the middle atmosphere

    Science.gov (United States)

    Mlynczak, Martin G.; Solomon, Susan

    1991-01-01

    The efficiency at which solar ultraviolet radiation absorbed in the Hartley band of ozone is directly converted to heat in the terrestrial mesosphere and lower thermosphere (50-110 km) is calculated. The ozone molecule undergoes photolysis to yield the excited species O(1D) and O2(1Delta) with a quantum yield of about 0.9. Spontaneous emission from O2(1Delta) and from O2(1Sigma) (excited by energy transfer from O/1D/) significantly decreases the amount of energy available for heat. Similarly, the efficiency at which solar ultraviolet radiation absorbed by O2 in the Schumann-Runge continuum is directly converted to heat in the lower thermosphere (95-110 km) is calculated. The O2 undergoes photolysis and the excited product O(1D) is generated. Spontaneous emission from O2(1Sigma) (excited by energy transfer from O/1D/) reduces the amount of energy available for heat in the lower thermosphere. The consideration of these energy transfer and loss processes results in significantly reduced heating rates as compared to those conventionally calculated in models of the middle atmosphere.

  12. Liquid metal heat exchanger for efficient heating of soils and geologic formations

    Science.gov (United States)

    DeVault, Robert C [Knoxville, TN; Wesolowski, David J [Kingston, TN

    2010-02-23

    Apparatus for efficient heating of subterranean earth includes a well-casing that has an inner wall and an outer wall. A heater is disposed within the inner wall and is operable within a preselected operating temperature range. A heat transfer metal is disposed within the outer wall and without the inner wall, and is characterized by a melting point temperature lower than the preselected operating temperature range and a boiling point temperature higher than the preselected operating temperature range.

  13. Heat wave Characteristics in the Eastern Mediterranean and Middle East using Extreme Value Theory

    Science.gov (United States)

    Tanarhte, Meryem; Hadjinicolaou, Panos; Lelieveld, Jos

    2015-04-01

    Heat waves in the eastern Mediterranean and Middle East can have large socioeconomic impacts. We apply a newly developed statistical framework, based on extreme value theory, to study the characteristics of heat waves in the region during the period 1973-2010 using data from fifteen measurement stations across the region. The analysis shows increasing trends in the highest daytime temperatures in the Persian Gulf region in summer. Increasing trends in the number of heat waves are found at all stations, whereas the maximum temperature during heat waves is found unchanged, implying no change in their intensity. Furthermore, no significant trends in the heat wave duration are also observed. Return levels are calculated for the individual hot days and found to be very high in the Persian Gulf region.

  14. Heat stress related dairy cow mortality during heat waves and control periods in rural Southern Ontario from 2010-2012.

    Science.gov (United States)

    Bishop-Williams, Katherine E; Berke, Olaf; Pearl, David L; Hand, Karen; Kelton, David F

    2015-11-27

    Heat stress is a physiological response to extreme environmental heat such as heat waves. Heat stress can result in mortality in dairy cows when extreme heat is both rapidly changing and has a long duration. As a result of climate change, heat waves, which are defined as 3 days of temperatures of 32 °C or above, are an increasingly frequent extreme weather phenomenon in Southern Ontario. Heat waves are increasing the risk for on-farm dairy cow mortality in Southern Ontario. Heat stress indices (HSIs) are generally based on temperature and humidity and provide a relative measure of discomfort which can be used to predict increased risk of on-farm dairy cow mortality. In what follows, the heat stress distribution was described over space and presented with maps. Similarly, on-farm mortality was described and mapped. The goal of this study was to demonstrate that heat waves and related HSI increases during 2010-2012 were associated with increased on-farm dairy cow mortality in Southern Ontario. Mortality records and farm locations for all farms registered in the CanWest Dairy Herd Improvement Program in Southern Ontario were retrieved for 3 heat waves and 6 three-day control periods from 2010 to 2012. A random sample of controls (2:1) was taken from the data set to create a risk-based hybrid design. On-farm heat stress was estimated using data from 37 weather stations and subsequently interpolated across Southern Ontario by geostatistical kriging. A Poisson regression model was applied to assess the on-farm mortality in relation to varying levels of the HSI. For every one unit increase in HSI the on-farm mortality rate across Southern Ontario increases by 1.03 times (CI95% (IRR) = (1.025,1.035); p = ≤ 0.001). With a typical 8.6 unit increase in HSI from a control period to a heat wave, mortality rates are predicted to increase by 1.27 times. Southern Ontario was affected by heat waves, as demonstrated by high levels of heat stress and increased on-farm mortality

  15. Energy efficient space and water heating in a university building

    OpenAIRE

    Schnurr, Birte

    2013-01-01

    The building Norra Djurgården 43:12 on the main campus of the Royal Institute of Technology (KTH)  in Stockholm will be retrofitted as students from the exter- nal campus Haninge will be moved there. This occasion is supposed to be used to improve the facility’s energy efficiency. Potential for this exists for both the space and the water heating system. The effect of decreasing the supply temperature to the radiators was examined  based on equations for the heat transfer. It was calcu- lated...

  16. Energetic Efficiency Evaluation by Using GroundWater Heat Pumps

    Directory of Open Access Journals (Sweden)

    Tokar Adriana

    2012-09-01

    Full Text Available Romania has significant energy potential from renewable sources, but the potential used is much lower due to technical and functional disadvantages, to economic efficiency, the cost elements and environmental limitations. However, efforts are being made to integrate renewable energy in the national energy system. To promote and encourage private investments for renewable energy utilization, programs have been created in order to access funds needed to implement these technologies. Assessment of such investments was carried out from technical and economical point of view, by analyzing a heat pump using as heat source the solar energy from the ground.

  17. The characteristic of heat wave effects on coronary heart disease mortality in Beijing, China: a time series study.

    Directory of Open Access Journals (Sweden)

    Zhaoxing Tian

    Full Text Available BACKGROUND: There is limited evidence for the impacts of heat waves on coronary heart disease (CHD mortality in Beijing, capital city of China. OBJECTIVES: We aimed to find a best heat wave definition for CHD mortality; and explore the characteristic of heat wave effects on CHD in Beijing, China. METHODS: We obtained daily data on weather and CHD mortality in Beijing for years 2000-2011. A quasi-Poisson regression model was used to assess the short-term impact of heat waves on CHD mortality in hot season (May-September, while controlling for relative humidity, day of the week, long-term trend and season. We compared 18 heat wave definitions by combining heat wave thresholds (87.5(th, 90.0(th, 92.5(th, 95(th, 97.5(th, and 99(th percentile of daily mean temperature with different duration days (≥ 2 to ≥ 4 days, using Akaike information criterion for quasi-Poisson. We examined whether heat wave effects on CHD mortality were modified by heat wave duration and timing. RESULTS: Heat wave definition using 97.5(th percentile of daily mean temperature (30.5 °C and duration ≥ 2 days produced the best model fit. Based on this heat wave definition, we found that men and elderly were sensitive to the first heat waves of the season, while women and young were sensitive to the second heat waves. In general, the longer duration of heat waves increased the risks of CHD mortality more than shorter duration for elderly. The first two days of heat waves had the highest impact on CHD mortality. Women and elderly were at higher risks than men and young when exposed to heat waves, but the effect differences were not statistically significant. CONCLUSIONS: Heat waves had significant impact on CHD mortality. This finding may have implications for policy making towards protecting human health from heat waves.

  18. Observation of Electron Bernstein Wave Heating in a Reversed Field Pinch

    Science.gov (United States)

    Seltzman, A. H.; Anderson, J. K.; Diem, S. J.; Goetz, J. A.; Forest, C. B.

    2017-11-01

    The first observation of rf heating in a reversed field pinch (RFP) using the electron Bernstein wave (EBW) is demonstrated on the Madison Symmetric Torus. Propagation across and heating in a stochastic magnetic field is observed. Novel techniques are required to measure the suprathermal electron tail generated by EBW heating in the presence of intense Ohmic heating. rf-heated electrons directly probe the edge transport properties in the RFP; measured loss rates imply a large noncollisional radial diffusivity.

  19. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants.

    Directory of Open Access Journals (Sweden)

    Simone Orsenigo

    Full Text Available Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy. The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and

  20. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants.

    Science.gov (United States)

    Orsenigo, Simone; Abeli, Thomas; Rossi, Graziano; Bonasoni, Paolo; Pasquaretta, Cristian; Gandini, Maurizia; Mondoni, Andrea

    2015-01-01

    Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence

  1. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants

    Science.gov (United States)

    Orsenigo, Simone; Abeli, Thomas; Rossi, Graziano; Bonasoni, Paolo; Pasquaretta, Cristian; Gandini, Maurizia; Mondoni, Andrea

    2015-01-01

    Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence

  2. Characterization of Heat Waves in the Sahel and associated mechanisms

    Science.gov (United States)

    Oueslati, Boutheina; Pohl, Benjamin; Moron, Vincent; Rome, Sandra

    2016-04-01

    Large efforts are made to investigate the heat waves (HW) in developed countries because of their devastating impacts on society, economy and environment. This interest increased after the intense event over Europe during summer 2003. However, HWs are still understudied over developing countries. This is particularly true in West Africa, and especially in the Sahel, where temperatures recurrently reach critical values, such as during the 2010 HW event. Understanding the Sahelian HWs and associated health risks constitute the main objective of ACASIS, a 4-year project funded by the French Agence Nationale de la Recherche. Our work contributes to this project and aims at characterizing the Sahelian HWs and understanding the mechanisms associated with such extreme events. There is no universal definition of a HW event, since it is highly dependent on the sector (human health, agriculture, transport...) and region of interest. In our case, a HW is defined when the heat index of the day and of the night exceeds the 90th percentile for at least 3 consecutive days (Rome et al. 2016, in preparation). This index combines temperature and relative humidity in order to determine the human-perceived equivalent temperature (definition adapted from Steadman, 1979). Intrinsic properties of Sahelian HW are analyzed from the Global Summary of the Day (GSOD) synoptic observations and ERA-interim reanalyses over 1979-2014 during boreal spring seasons (April-May-June), the warmest period of the year in the Central Sahel. ERA-interim captures well the observed interannual variability and seasonal cycle at the regional scale, as well as the 1979-2014 increasing linear trend of springtime HW occurrences in the Sahel. Reanalyses, however, overestimate the duration, spatial extent of HW, and underestimate their intensity. For both GSOD and ERA-interim, we show that, over the last three decades, Sahelian HWs tend to become more frequent, last longer, cover larger areas and reach higher

  3. Health impacts of the July 2010 heat wave in Québec, Canada

    Directory of Open Access Journals (Sweden)

    Bustinza Ray

    2013-01-01

    Full Text Available Abstract Background One of the consequences of climate change is the increased frequency and intensity of heat waves which can cause serious health impacts. In Québec, July 2010 was marked by an unprecedented heat wave in recent history. The purpose of this study is to estimate certain health impacts of this heat wave. Methods The crude daily death and emergency department admission rates during the heat wave were analyzed in relation to comparison periods using 95% confidence intervals. Results During the heat wave, the crude daily rates showed a significant increase of 33% for deaths and 4% for emergency department admissions in relation to comparison periods. No displacement of mortality was observed over a 60-day horizon. Conclusions The all-cause death indicator seems to be sufficiently sensitive and specific for surveillance of exceedences of critical temperature thresholds, which makes it useful for a heat health-watch system. Many public health actions combined with the increased use of air conditioning in recent decades have contributed to a marked reduction in mortality during heat waves. However, an important residual risk remains, which needs to be more vigorously addressed by public health authorities in light of the expected increase in the frequency and severity of heat waves and the aging of the population.

  4. Unraveling anthropogenic influence on the changing risk of heat waves in China

    Science.gov (United States)

    Sun, Qiaohong; Miao, Chiyuan; AghaKouchak, Amir; Duan, Qingyun

    2017-05-01

    Heat waves trigger substantial social and environmental impacts and even cause massive civilian casualties in extreme cases. Observations show the areas affected by heat waves have increased over China, with the most extreme heat wave occurring during the past five decades. Here we show that both trends can be attributed to anthropogenic influences. We report that under the moderate Representative Concentration Pathways 4.5 scenario, anthropogenic influences will increase the risk of occurrence of the observed maximum Heat Wave Magnitude Index in the late 21st century and will cause a more than tenfold increase in the likelihood of the strongest events on record recurring across more than half China. More than 50% of land area in China is projected to be affected by intense heat waves. Our results show that over eastern China, the extremes in heat distribution are more sensitive to precipitation deficits, indicating stronger heat wave amplification trends to occur under drier conditions. The likelihood of concurrent droughts and heat waves is expected to increase in large parts of China in the late 21st century.

  5. High-efficiency shock-wave generator for extracorporeal lithotripsy.

    Science.gov (United States)

    Broyer, P; Cathignol, D; Theillère, Y; Mestas, J L

    1996-09-01

    In extracorporeal lithotripsy, the electro-acoustic efficiency of electrohydraulic generators is limited by the inductance of the electrical discharge circuit. A new shock-wave generator is described that uses a coaxial discharge line enabling electro-acoustic efficiency to be greatly increased. The line is built using a para-electric ceramic with a relative dielectric constant of 1700, manufactured for use in high-voltage impulse mode. A coaxial spark gap, with minimal inductance, has been developed to obtain the triggered breakdown of the discharge line. Shock waves are created with a coaxial electrode plugged directly into the spark gap and immersed in an electrolyte of degassed saline. Electrode gap and electrolyte resistivity are adjusted to match the resistivity of the electrolyte volume between the underwater electrodes to the characteristic impedance of the line. The discharge line generates in the medium a rectangular current pulse with an amplitude of about 6000 A and a rise time of 50 ns. Compared with conventional generators, measurements of the expansive peak pressure pulse show an increase of 105% at 10 kV, 86.5% at 12 kV and 34.5% at 14 kV charging voltage. Electro-acoustic efficiency is found to be 11% instead of 5.5% for a conventional discharge circuit.

  6. The computational optimization of heat exchange efficiency in stack chimneys

    Energy Technology Data Exchange (ETDEWEB)

    Van Goch, T.A.J.

    2012-02-15

    For many industrial processes, the chimney is the final step before hot fumes, with high thermal energy content, are discharged into the atmosphere. Tapping into this energy and utilizing it for heating or cooling applications, could improve sustainability, efficiency and/or reduce operational costs. Alternatively, an unused chimney, like the monumental chimney at the Eindhoven University of Technology, could serve as an 'energy channeler' once more; it can enhance free cooling by exploiting the stack effect. This study aims to identify design parameters that influence annual heat exchange in such stack chimney applications and optimize these parameters for specific scenarios to maximize the performance. Performance is defined by annual heat exchange, system efficiency and costs. The energy required for the water pump as compared to the energy exchanged, defines the system efficiency, which is expressed in an efficiency coefficient (EC). This study is an example of applying building performance simulation (BPS) tools for decision support in the early phase of the design process. In this study, BPS tools are used to provide design guidance, performance evaluation and optimization. A general method for optimization of simulation models will be studied, and applied in two case studies with different applications (heating/cooling), namely; (1) CERES case: 'Eindhoven University of Technology monumental stack chimney equipped with a heat exchanger, rejects heat to load the cold source of the aquifer system on the campus of the university and/or provides free cooling to the CERES building'; and (2) Industrial case: 'Heat exchanger in an industrial stack chimney, which recoups heat for use in e.g. absorption cooling'. The main research question, addressing the concerns of both cases, is expressed as follows: 'what is the optimal set of design parameters so heat exchange in stack chimneys is optimized annually for the cases in which a

  7. Modification of land-atmosphere interactions by CO2 effects: Implications for summer dryness and heat wave amplitude

    Science.gov (United States)

    Lemordant, Léo.; Gentine, Pierre; Stéfanon, Marc; Drobinski, Philippe; Fatichi, Simone

    2016-10-01

    Plant stomata couple the energy, water, and carbon cycles. We use the framework of Regional Climate Modeling to simulate the 2003 European heat wave and assess how higher levels of surface CO2 may affect such an extreme event through land-atmosphere interactions. Increased CO2 modifies the seasonality of the water cycle through stomatal regulation and increased leaf area. As a result, the water saved during the growing season through higher water use efficiency mitigates summer dryness and the heat wave impact. Land-atmosphere interactions and CO2 fertilization together synergistically contribute to increased summer transpiration. This, in turn, alters the surface energy budget and decreases sensible heat flux, mitigating air temperature rise. Accurate representation of the response to higher CO2 levels and of the coupling between the carbon and water cycles is therefore critical to forecasting seasonal climate, water cycle dynamics, and to enhance the accuracy of extreme event prediction under future climate.

  8. High Power Fast Wave Coupling and Heating in H-mode Plasmas on DIII-D

    Science.gov (United States)

    Pinsker, R. I.; Buttery, R. J.; Luce, T. C.; Porkolab, M.; Diem, S.; Kaufman, M.; Ryan, P. M.; Hosea, J. C.; Nagy, A.; Perkins, R.; Solomon, W. M.; Maggiora, R.; Milanesio, D.

    2012-10-01

    Up to 2.5 MW of fast wave (FW) heating power has been coupled to the core of ELMing H-mode discharges with βN<=2.5 in conjunction with 3-7 MW of neutral beam injection and 2.6 MW of electron cyclotron heating. Core FW heating efficiency has been found experimentally to approach 100% in the Advanced Inductive regime, consistent with the excellent absorption predicted by ray-tracing models in this high βe regime. Low antenna loading (high rf voltages) characteristic of such regimes makes increasing the FW power challenging. A study of techniques to enhance FW antenna loading has been carried out in DIII-D, with emphasis on maintenance of good confinement. The loading is in absolute agreement with modeling when edge density profiles measured with reflectometry are used in the model. Recent work extending the range of H-mode regimes to which FW heating has been applied and on increasing the FW power coupled to those regimes is described.

  9. EFFICIENCY AND LIFETIME OF SOLAR COLLECTORS FOR SOLAR HEATING PLANTS

    OpenAIRE

    Fan, Jianhua; Chen, Ziqian; Furbo, Simon; Perers, Bengt; Karlsson, Björn

    2009-01-01

    The 12.5 m² flat plate solar collector HT, today marketed by Arcon Solvarme A/S, has been used in solar heating plants in Scandinavia since 1983. The collector is designed to operate in a temperature interval between 40°C and 90°C. The efficiency of the collector has been strongly improved since it was introduced on the market. The paper will present the increase of the efficiency of the collector due to technical improvements since 1983. Further, measurements from the spring of 2009 of the e...

  10. Electron transport in Tore Supra with fast wave electron heating

    Energy Technology Data Exchange (ETDEWEB)

    Hoang, G.T.; Aniel, T.; Ottaviani, M.; Garbet, X. [CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint-Paul-lez-Durance (France); Horton, W.; Zhu, P. [University of Texas at Austin (United States). Inst. for Fusion Studies

    1999-09-15

    The hot electron plasmas (T{sub e} > 2T{sub i}) in Tore Supra driven by Fast Wave Electron Heating (FWEH) are analyzed for thermal transport. Both neoclassical and anomalous transport processes are taken into account. The dominant power flow is through the electron channel of anomalous thermal diffusivity. The electron and ion temperature gradient driven instabilities are analyzed for a well documented discharge and shown to explain the diffusivities inferred from the steady power balance analysis. The discharges are maintained in a quasi-steady state for periods up to one hundred global energy replacement times. A large Tore S database is tested against two models for the turbulent electron thermal conductivity Good correlation is obtained with an updated version of the collisionless skin depth formula. The electrostatic turbulence-based formula performs poorly in the core but well in the outer plasma. The electromagnetic turbulence theory based formula is benchmarked with the empirical Taroni-Bohm formula derived from JET data. (author)

  11. India heat wave attribution considering effects of anthropogenic aerosols.

    Science.gov (United States)

    Haustein, Karsten; Otto, Friederike; Allen, Myles; Cullen, Heidi

    2017-04-01

    Extreme weather event attribution, now a well-established field within the Detection and Attribution community, slowly incorporates all regions of the globe. Here we present heat wave results for India in 2015, using pre-conditioned (SST driven) large ensemble RCM simulations provided by weather@home. Apart from the presentation of a thoroughly validated set of hydrometeorological model variables for the South Asian region, the novelty in this study is that we include a GHG-only ensemble in our analysis. Rather than relying on actual and counterfactual data for 2015 to investigate the event-specific dynamic contribution, we make also use of an ensemble where the SST forcing corresponds to a world in which anthropogenic aerosols have been removed (AA). Since AAs have far-reaching implications for the Asian monsoon system (e.g. Bollasina et al. 2011; Li et al 2016), the changing risk of certain extreme weather events occurring due to a variable load of AAs can potentially be attributed for the first time. Since we are now in the possession a fully consistent 30 year climatology (200 ensemble member per year) for actual, counterfactual and GHG only conditions as well, we can try and answer the question whether circulation changes or trends due to anthropogenic climate change are detectable already. In addition, we demonstrate how these results can be used in our fast track attribution framework, including evidence for the robustness of the analogue method utilised to determine event-specific dynamic contributions.

  12. High-efficiency Commercial Cold Climate Heat Pump

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Ahmad M. [United Technologies Research Center, East Hartford, CT (United States); Cogswell, F. [United Technologies Research Center, East Hartford, CT (United States); Verma, P. [United Technologies Research Center, East Hartford, CT (United States)

    2015-08-28

    United Technologies Research Center (UTRC) proposed in 2012 to design, develop and demonstrate an air-source 10TR high-efficiency commercial cold climate heat pump (CCCHP). The proposed heat pump would be scalable beyond 40TR, cost effective with a simple payback of < 3 years upon commercialization and would reduce annual electricity use for building space heating in cold climates by at least 20%. This would represent an annual savings of $2.3 billion and a 20% displacement of total greenhouse gases generated upon full commercialization. The primary objective was to develop a highly integrated system that shall meet or exceed DOE capacity and efficiency targets at key conditions and is scalable, cost-effective and simple relative to the state-of-the-art. Specifically, the goal of the project was to design, develop and demonstrate a CCCHP that exceeds DOE capacity degradation requirements at +17F and -13F conditions (0 and <15% degradation vs. 10 and 25% DOE requirements, respectively) while meeting or exceeding DOE capacity and system efficiency requirements at all other conditions.

  13. Performance optimization of Brayton heat engine at maximum efficient power using temperature dependent specific heat of working fluid

    OpenAIRE

    Kumar, Rajesh; Kaushik, S C; Kumar, Raj

    2015-01-01

    Efficient power optimization of Brayton heat engine with variable specific heat of the working fluid is analyzed from the view of finite time thermodynamics. The efficient power is defined as the multiplication of engine power and engine efficiency. Hence, the proposed method considers not only the power output but also the engine efficiency. Optimizing the efficient power gives a compromise between power and engine efficiency. Results obtained are compared with those obtained by using the ma...

  14. Detection of heat and cold waves in Montevergine time series (1884-2015)

    Science.gov (United States)

    Capozzi, Vincenzo; Budillon, Giorgio

    2017-05-01

    In recent years, extreme events related to cooling and heating have taken high resonance, motivating the scientific community to carry out an intensive research activity, aimed to detect their variability and frequency. In this work, we have investigated about the frequency, the duration, the severity and the intensity of heat and cold waves in a Southern Italy high-altitude region, by analysing the climatological time series collected in Montevergine observatory. Following the guidelines provided by CLIVAR project (Climate and Ocean Variability, Predictability and Change), we have adopted indicators based on percentiles and duration to define a heat wave and cold event. Main results have highlighted a strong and significant positive trend in the last 40 years (1974-2015) in heat waves frequency, severity and intensity. On the contrary, in recent decades, cold wave events have exhibited a significant and positive trend only in intensity. Moreover, through the usage of two Wavelet Analysis tools, the Cross Wavelet Transform and the Wavelet Coherence, we have investigated about the connections between the extreme temperature events occurred in Montevergine and the large-scale atmospheric patterns. The heat wave events have exhibited relevant relationships with the Western European Zonal Circulation and the North Atlantic Oscillation, whereas the variability of cold wave events have shown linkages with the Eastern Mediterranean Pattern and the North Sea Caspian Pattern. In addition, the main features of synoptic patterns that have caused summer heat waves and winter cold waves in Montevergine site are presented.

  15. Ambient temperature and added heat wave effects on hospitalizations in California from 1999 to 2009.

    Science.gov (United States)

    Sherbakov, Toki; Malig, Brian; Guirguis, Kristen; Gershunov, Alexander; Basu, Rupa

    2018-01-01

    Investigators have examined how heat waves or incremental changes in temperature affect health outcomes, but few have examined both simultaneously. We utilized distributed lag nonlinear models (DLNM) to explore temperature associations and evaluate possible added heat wave effects on hospitalizations in 16 climate zones throughout California from May through October 1999-2009. We define heat waves as a period when daily mean temperatures were above the zone- and month-specific 95th percentile for at least two consecutive days. DLNMs were used to estimate climate zone-specific non-linear temperature and heat wave effects, which were then combined using random effects meta-analysis to produce an overall estimate for each. With higher temperatures, admissions for acute renal failure, appendicitis, dehydration, ischemic stroke, mental health, non-infectious enteritis, and primary diabetes were significantly increased, with added effects from heat waves observed for acute renal failure and dehydration. Higher temperatures also predicted statistically significant decreases in hypertension admissions, respiratory admissions, and respiratory diseases with secondary diagnoses of diabetes, though heat waves independently predicted an added increase in risk for both respiratory types. Our findings provide evidence that both heat wave and temperature exposures can exert effects independently. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Evaluation of major heat waves' mechanisms in EURO-CORDEX RCMs over Central Europe

    Science.gov (United States)

    Lhotka, Ondřej; Kyselý, Jan; Plavcová, Eva

    2017-09-01

    The main aim of the study is to evaluate the capability of EURO-CORDEX regional climate models (RCMs) to simulate major heat waves in Central Europe and their associated meteorological factors. Three reference major heat waves (1994, 2006, and 2015) were identified in the E-OBS gridded data set, based on their temperature characteristics, length and spatial extent. Atmospheric circulation, precipitation, net shortwave radiation, and evaporative fraction anomalies during these events were assessed using the ERA-Interim reanalysis. The analogous major heat waves and their links to the aforementioned factors were analysed in an ensemble of EURO-CORDEX RCMs driven by various global climate models in the 1970-2016 period. All three reference major heat waves were associated with favourable circulation conditions, precipitation deficit, reduced evaporative fraction and increased net shortwave radiation. This joint contribution of large-scale circulation and land-atmosphere interactions is simulated with difficulties in majority of the RCMs, which affects the magnitude of modelled major heat waves. In some cases, the seemingly good reproduction of major heat waves' magnitude is erroneously achieved through extremely favourable circulation conditions compensated by a substantial surplus of soil moisture or vice versa. These findings point to different driving mechanisms of major heat waves in some RCMs compared to observations, which should be taken into account when analysing and interpreting future projections of these events.

  17. Detection of heat wave using Kalpana-1 VHRR land surface temperature product over India

    Science.gov (United States)

    Shah, Dhiraj; Pandya, Mehul R.; Pathak, Vishal N.; Darji, Nikunj P.; Trivedi, Himanshu J.

    2016-05-01

    Heat Waves can have notable impacts on human mortality, ecosystem, economics and energy supply. The effect of heat wave is much more intense during summer than the other seasons. During the period of April to June, spells of very hot weather occur over certain regions of India and global warming scenario may result in further increases of such temperature anomalies and corresponding heat waves conditions. In this paper, satellite observations have been used to detect the heat wave conditions prevailing over India for the period of May-June 2015. The Kalpana-1 VHRR derived land surface temperature (LST) products have been used in the analysis to detect the heat wave affected regions over India. Results from the analysis shows the detection of heat wave affected pixels over Indian land mass. It can be seen that during the study period the parts of the west India, Indo-gangetic plane, Telangana and part of Vidarbh was under severe heat wave conditions which is also confirmed with Automatic Weather Station (AWS) air temperature observations.

  18. Efficiency of utilization of heat of moisture from exhaust gases of heat HRSG of CCGT

    Directory of Open Access Journals (Sweden)

    Galashov Nikolay

    2017-01-01

    Full Text Available The paper discusses the technology of utilizing the heat of exhaust gas moisture from heat recovery steam gases (HRSG of combined-cycle gas turbine (CCGT. Particular attention focused on the influence of the excess air factor on the trapping of the moisture of the exhaust gases, as in the HRSG of the CCGT its value varies over a wider range than in the steam boilers of the TPP. For the research, has been developed a mathematical model that allows to determine the volumes of combustion products and the amount of water vapor produced according to a given composition of the burned gas and determine the amount of moisture that will be obtained as a result of condensation at a given temperature of the flue gases at the outlet of the condensation heat exchanger (CHE. To calculate the efficiency of the HRSG taking into account the heat of condensation of moisture in the CHE an equation is derived.

  19. The role of spring precipitation deficits on European and North American summer heat wave activity

    Science.gov (United States)

    Cowan, Tim; Hegerl, Gabi

    2017-04-01

    Heat waves are relatively short-term climate phenomena with potentially severe societal impacts, particularly on health, agriculture and the natural environment. In water-limited regions, increased heat wave activity over intra-decadal periods is often associated with protracted droughts, as observed over North America's Central and Southern Great Plains in the 1930s and 1950s, highlighting the importance of land surface-atmosphere feedbacks. Here we present an analysis of the covariability of spring precipitation deficit and summer heat waves for North America and Europe, the latter having experienced an increase in summer heat wave frequency since the 1950s (Perkins et al. 2012). Over the Great Plains summer heat waves are significantly earlier, longer and hotter if following dry rather than wet springs, with the mega-heat waves of the 1930s Dust Bowl decade an extreme example (e.g. Cowan et al. 2017). Similar relationships can be found in some parts of Europe for heat wave frequency and duration, namely Southern and Eastern Europe, although the heat wave timing and amplitude (i.e. the hottest events) appear less sensitive to spring drying. Climate model results investigating the relationship between heat waves and precipitation deficit in regions in Europe and North America will also be presented. It is necessary to pinpoint the causes of large decadal variations in heat wave metrics, as seen in the 1930s over North America and more recently across Central Europe, for event attribution purposes and to improve near-decadal prediction. The tight link between spring drought and summer heat waves will also be important for understanding the impacts of these climatic events and supports the development of compound event analysis techniques. References: Cowan, T., G. Hegerl, I. Colfescu, A. Purich and G. Boshcat (2016), Factors contributing to record-breaking heat waves over the Great Plains during the 1930s Dust Bowl. Journal of Climate, doi: 10.1175/JCLI-D-16

  20. Efficiency Analysis of a Wave Power Generation System by Using Multibody Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Soo; Sohn, Jeong Hyun [Pukyong National Univ., Busan (Korea, Republic of); Kim, Jung Hee; Sung, Yong Jun [INGINE Inc., Seoul (Korea, Republic of)

    2016-06-15

    The energy absorption efficiency of a wave power generation system is calculated as the ratio of the wave power to the power of the system. Because absorption efficiency depends on the dynamic behavior of the wave power generation system, a dynamic analysis of the wave power generation system is required to estimate the energy absorption efficiency of the system. In this study, a dynamic analysis of the wave power generation system under wave loads is performed to estimate the energy absorption efficiency. RecurDyn is employed to carry out the dynamic analysis of the system, and the Morison equation is used for the wave load model. According to the results, the lower the wave height and the shorter the period, the higher is the absorption efficiency of the system.

  1. Induction-heating MOCVD reactor with significantly improved heating efficiency and reduced harmful magnetic coupling

    KAUST Repository

    Li, Kuang-Hui

    2018-02-23

    In a conventional induction-heating III-nitride metalorganic chemical vapor deposition (MOCVD) reactor, the induction coil is outside the chamber. Therefore, the magnetic field does not couple with the susceptor well, leading to compromised heating efficiency and harmful coupling with the gas inlet and thus possible overheating. Hence, the gas inlet has to be at a minimum distance away from the susceptor. Because of the elongated flow path, premature reactions can be more severe, particularly between Al- and B-containing precursors and NH3. Here, we propose a structure that can significantly improve the heating efficiency and allow the gas inlet to be closer to the susceptor. Specifically, the induction coil is designed to surround the vertical cylinder of a T-shaped susceptor comprising the cylinder and a top horizontal plate holding the wafer substrate within the reactor. Therefore, the cylinder coupled most magnetic field to serve as the thermal source for the plate. Furthermore, the plate can block and thus significantly reduce the uncoupled magnetic field above the susceptor, thereby allowing the gas inlet to be closer. The results show approximately 140% and 2.6 times increase in the heating and susceptor coupling efficiencies, respectively, as well as a 90% reduction in the harmful magnetic flux on the gas inlet.

  2. Factors Influencing the Thermal Efficiency of Horizontal Ground Heat Exchangers

    Directory of Open Access Journals (Sweden)

    Eloisa Di Sipio

    2017-11-01

    Full Text Available The performance of very shallow geothermal systems (VSGs, interesting the first 2 m of depth from ground level, is strongly correlated to the kind of sediment locally available. These systems are attractive due to their low installation costs, less legal constraints, easy maintenance and possibility for technical improvements. The Improving Thermal Efficiency of horizontal ground heat exchangers Project (ITER aims to understand how to enhance the heat transfer of the sediments surrounding the pipes and to depict the VSGs behavior in extreme thermal situations. In this regard, five helices were installed horizontally surrounded by five different backfilling materials under the same climatic conditions and tested under different operation modes. The field test monitoring concerned: (a monthly measurement of thermal conductivity and moisture content on surface; (b continuous recording of air and ground temperature (inside and outside each helix; (c continuous climatological and ground volumetric water content (VWC data acquisition. The interactions between soils, VSGs, environment and climate are presented here, focusing on the differences and similarities between the behavior of the helix and surrounding material, especially when the heat pump is running in heating mode for a very long time, forcing the ground temperature to drop below 0 °C.

  3. Increased heat waves with loss of irrigation in the United States

    Science.gov (United States)

    Lu, Yaqiong; Kueppers, Lara

    2015-06-01

    A potential decline in irrigation due to groundwater depletion or insufficient surface water would not only directly affect agriculture, but also could alter surface climate. In this study we investigated how loss of irrigation affects heat wave frequency, duration, and intensity across fifteen heat wave indices (HINs) using a regional climate model that incorporated dynamic crop growth. Averaged across all indices, loss of irrigation increased heat wave frequency, duration, and intensity. In the United States, irrigation effects on heat waves were statistically significant over irrigated cropland for the majority of HINs, but in non-irrigated regions, the effects were significant only for a few HINs. The heat index temperature metrics that include humidity were less sensitive to loss of irrigation due to the trade-off between increased temperature and decreased humidity. Using the same temperature metric but different temperature thresholds resulted in qualitatively similar effects on heat waves. Regions experiencing strong groundwater depletion, such as the southern high plains, may suffer more and longer heat waves with reduced irrigation.

  4. Work output and efficiency at maximum power of linear irreversible heat engines operating with a finite-sized heat source.

    Science.gov (United States)

    Izumida, Yuki; Okuda, Koji

    2014-05-09

    We formulate the work output and efficiency for linear irreversible heat engines working between a finite-sized hot heat source and an infinite-sized cold heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the heat engines operate at the maximum power under the tight-coupling condition without heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart.

  5. Efficient numerical simulation of heat storage in subsurface georeservoirs

    Science.gov (United States)

    Boockmeyer, A.; Bauer, S.

    2015-12-01

    The transition of the German energy market towards renewable energy sources, e.g. wind or solar power, requires energy storage technologies to compensate for their fluctuating production. Large amounts of energy could be stored in georeservoirs such as porous formations in the subsurface. One possibility here is to store heat with high temperatures of up to 90°C through borehole heat exchangers (BHEs) since more than 80 % of the total energy consumption in German households are used for heating and hot water supply. Within the ANGUS+ project potential environmental impacts of such heat storages are assessed and quantified. Numerical simulations are performed to predict storage capacities, storage cycle times, and induced effects. For simulation of these highly dynamic storage sites, detailed high-resolution models are required. We set up a model that accounts for all components of the BHE and verified it using experimental data. The model ensures accurate simulation results but also leads to large numerical meshes and thus high simulation times. In this work, we therefore present a numerical model for each type of BHE (single U, double U and coaxial) that reduces the number of elements and the simulation time significantly for use in larger scale simulations. The numerical model includes all BHE components and represents the temporal and spatial temperature distribution with an accuracy of less than 2% deviation from the fully discretized model. By changing the BHE geometry and using equivalent parameters, the simulation time is reduced by a factor of ~10 for single U-tube BHEs, ~20 for double U-tube BHEs and ~150 for coaxial BHEs. Results of a sensitivity study that quantify the effects of different design and storage formation parameters on temperature distribution and storage efficiency for heat storage using multiple BHEs are then shown. It is found that storage efficiency strongly depends on the number of BHEs composing the storage site, their distance and

  6. On the long term climatology and trends of heat and cold waves over ...

    Indian Academy of Sciences (India)

    10

    shown significant decreasing trend in heat waves (2 stations from north India ..... Cambridge University Press, Cambridge UK and New York N Y USA 582 pp. ... Board, Department of Science and Technology (SERB-DST), New Delhi, India.

  7. Chiral heat wave in cold Fermi liquid and modified zero sound

    Science.gov (United States)

    Frenklakh, D.; Gorsky, A.

    2017-08-01

    We discuss kinetic equations involving the anomalous terms responsible for the chiral anomaly. The general chiral heat wave in cold Fermi liquid is described and the modification of the anomalous zero sound at small temperature and vorticity is found.

  8. Detection of heat and cold waves in Montevergine time series (1884–2015)

    National Research Council Canada - National Science Library

    Vincenzo Capozzi; Giorgio Budillon

    2017-01-01

    .... In this work, we have investigated about the frequency, the duration, the severity and the intensity of heat and cold waves in a Southern Italy high-altitude region, by analysing the climatological...

  9. Heat transfer and energy efficiency in infrared paper dryers

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Magnus

    1999-11-01

    Infrared (IR) dryers are widely used in the paper industry, mainly in the production of coated paper grades. The thesis deals with various aspects of heat transfer and energy use in infrared heaters and dryers as employed in the paper industry. Both gas-fired and electric IR dryers are considered and compared. The thesis also provides an introduction to infrared heaters and infrared drying, including a review of recent literature in the field. The transport of thermal radiation inside a paper sheet was investigated and different IR dryers were compared in terms of their ability to transfer energy to the internal parts of a paper sheet. Although there were evident differences in the absorption of radiation between gas-fired and electric IR dryers, the distinction was found not to be as important as has generally been believed. The main differences appeared to be due to the choice of a one- or a two-sided dryer solution, rather than the spectral distributions emitted by the dryers. A method for evaluating the radiation efficiency of IR heaters was proposed. An electric IR heater was evaluated in the laboratory. The radiation efficiency of the heater was shown to be strongly dependent on the power level. The maximum efficiency, found at high power level, was close to 60 %. A procedure for evaluation of the total energy transfer efficiency of an infrared paper dryer was proposed and used in the evaluation of an electric IR dryer operating in an industrial coating machine. The efficiency of the dryer was roughly 40 %. A model for an electric IR heater was developed. The model includes non-grey radiative heat transfer between the different parts of the heater, as well as conduction in reflector material and convective cooling of the surfaces. Using IR module voltage as the only input, model predictions of temperatures and heat flux were found to agree well with experimental data both at steady state and under transient conditions. The model was also extended to include

  10. Coupling of an acoustic wave to shear motion due to viscous heating

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin; Goree, J. [Department of Physics and Astronomy, The University of Iowa, Iowa City, Iowa 52242 (United States)

    2016-07-15

    Viscous heating due to shear motion in a plasma can result in the excitation of a longitudinal acoustic wave, if the shear motion is modulated in time. The coupling mechanism is a thermal effect: time-dependent shear motion causes viscous heating, which leads to a rarefaction that can couple into a longitudinal wave, such as an acoustic wave. This coupling mechanism is demonstrated in an electrostatic three-dimensional (3D) simulation of a dusty plasma, in which a localized shear flow is initiated as a pulse, resulting in a delayed outward propagation of a longitudinal acoustic wave. This coupling effect can be profound in plasmas that exhibit localized viscous heating, such as the dusty plasma we simulated using parameters typical of the PK-4 experiment. We expect that a similar phenomenon can occur with other kinds of plasma waves.

  11. The Role Of Torsional Alfvén Waves in Coronal Heating

    Science.gov (United States)

    Antolin, P.; Shibata, K.

    2010-03-01

    In the context of coronal heating, among the zoo of magnetohydrodynamic (MHD) waves that exist in the solar atmosphere, Alfvén waves receive special attention. Indeed, these waves constitute an attractive heating agent due to their ability to carry over the many different layers of the solar atmosphere sufficient energy to heat and maintain a corona. However, due to their incompressible nature these waves need a mechanism such as mode conversion (leading to shock heating), phase mixing, resonant absorption, or turbulent cascade in order to heat the plasma. Furthermore, their incompressibility makes their detection in the solar atmosphere very difficult. New observations with polarimetric, spectroscopic, and imaging instruments such as those on board the Japanese satellite Hinode, or the Crisp spectropolarimeter of the Swedish Solar Telescope or the Coronal Multi-channel Polarimeter, are bringing strong evidence for the existence of energetic Alfvén waves in the solar corona. In order to assess the role of Alfvén waves in coronal heating, in this work we model a magnetic flux tube being subject to Alfvén wave heating through the mode conversion mechanism. Using a 1.5 dimensional MHD code, we carry out a parameter survey varying the magnetic flux tube geometry (length and expansion), the photospheric magnetic field, the photospheric velocity amplitudes, and the nature of the waves (monochromatic or white-noise spectrum). The regimes under which Alfvén wave heating produces hot and stable coronae are found to be rather narrow. Independently of the photospheric wave amplitude and magnetic field, a corona can be produced and maintained only for long (>80 Mm) and thick (area ratio between the photosphere and corona >500) loops. Above a critical value of the photospheric velocity amplitude (generally a few km s-1) the corona can no longer be maintained over extended periods of time and collapses due to the large momentum of the waves. These results establish several

  12. Mapping heat wave risk in the UK: Proactive planning for the 2050s

    Science.gov (United States)

    Oven, Katie; Reaney, Sim; Ohlemüller, Ralf; Nodwell, Sarah; Curtis, Sarah; Riva, Mylène; Dunn, Christine; Val, Dimitri; Burkhard, Roland

    2010-05-01

    Climate change projections suggest an increased frequency of heat waves in the UK over the coming decades. Such extreme events pose a serious threat to human health and are likely to impact upon health and social care systems and the infrastructures supporting them. This stress will result from both increased demands upon healthcare services and the ability of the infrastructure to cope, such as sufficient climate control in hospitals. Certain sectors of the population, such as older people, have an increased susceptibility to heat waves and hence are the focus of this research. There is no universal definition of a heat wave, reflecting the acclimatisation of a population. Based on a review of the literature, this research therefore sets out a series of working definitions of a heat wave in the UK context from a human health perspective. Drawing on these definitions, the UK heat wave hazard was mapped for the 2050s (2040-2069) using daily minimum and maximum temperature data derived from the UKCP09 Weather Generator at 50 km resolution. The analysis was undertaken for the three different greenhouse gas emissions scenarios within UKCP09 (low, medium and high). Hot spots of increased heat wave risk were identified and comparisons made between the various model outputs. These data were then combined with demographic forecasts for the 2050s enabling the identification of areas with an ageing population. Results are presented showing the scale of the projected change in heat wave risk across the UK and the location of older people. These results will be used in proactive planning to help policymakers and practitioners respond more appropriately to the needs of vulnerable populations in the coming decades. Key words: climate change; heat wave; risk mapping; vulnerability; risk reduction.

  13. Simulation of heat waves in climate models using large deviation algorithms

    Science.gov (United States)

    Ragone, Francesco; Bouchet, Freddy; Wouters, Jeroen

    2016-04-01

    One of the goals of climate science is to characterize the statistics of extreme, potentially dangerous events (e.g. exceptionally intense precipitations, wind gusts, heat waves) in the present and future climate. The study of extremes is however hindered by both a lack of past observational data for events with a return time larger than decades or centuries, and by the large computational cost required to perform a proper sampling of extreme statistics with state of the art climate models. The study of the dynamics leading to extreme events is especially difficult as it requires hundreds or thousands of realizations of the dynamical paths leading to similar extremes. We will discuss here a new numerical algorithm, based on large deviation theory, that allows to efficiently sample very rare events in complex climate models. A large ensemble of realizations are run in parallel, and selection and cloning procedures are applied in order to oversample the trajectories leading to the extremes of interest. The statistics and characteristic dynamics of the extremes can then be computed on a much larger sample of events. This kind of importance sampling method belongs to a class of genetic algorithms that have been successfully applied in other scientific fields (statistical mechanics, complex biomolecular dynamics), allowing to decrease by orders of magnitude the numerical cost required to sample extremes with respect to standard direct numerical sampling. We study the applicability of this method to the computation of the statistics of European surface temperatures with the Planet Simulator (Plasim), an intermediate complexity general circulation model of the atmosphere. We demonstrate the efficiency of the method by comparing its performances against standard approaches. Dynamical paths leading to heat waves are studied, enlightening the relation of Plasim heat waves with blocking events, and the dynamics leading to these events. We then discuss the feasibility of this

  14. Quantification and assessment of heat and cold waves in Novi Sad, Northern Serbia.

    Science.gov (United States)

    Basarin, Biljana; Lukić, Tin; Matzarakis, Andreas

    2016-01-01

    Physiologically equivalent temperature (PET) has been applied to the analysis of heat and cold waves and human thermal conditions in Novi Sad, Serbia. A series of daily minimum and maximum air temperature, relative humidity, wind, and cloud cover was used to calculate PET for the investigated period 1949-2012. The heat and cold wave analysis was carried out on days with PET values exceeding defined thresholds. Additionally, the acclimatization approach was introduced to evaluate human adaptation to interannual thermal perception. Trend analysis has revealed the presence of increasing trend in summer PET anomalies, number of days above defined threshold, number of heat waves, and average duration of heat waves per year since 1981. Moreover, winter PET anomaly as well as the number of days below certain threshold and number of cold waves per year until 1980 was decreasing, but the decrease was not statistically significant. The highest number of heat waves during summer was registered in the last two decades, but also in the first decade of the investigated period. On the other hand, the number of cold waves during six decades is quite similar and the differences are very small.

  15. Generation of ELF waves during HF heating of the ionosphere at midlatitudes

    Science.gov (United States)

    Sharma, A. S.; Eliasson, B.; Shao, X.; Papadopoulos, K.

    2016-07-01

    Modulated high-frequency radio frequency heating of the ionospheric F region produces a local modulation of the electron temperature, and the resulting pressure gradient gives rise to a diamagnetic current. The oscillations of the diamagnetic current excite hydromagnetic waves in the ELF range that propagate away from the heated region. The generation of the waves in the 2-10 Hz range by a modulated heating in the midlatitude ionosphere is studied using numerical simulations of a collisional Hall-magnetohydrodynamic model. To model the plasma processes in the midlatitude ionosphere the Earth's dipole magnetic field and typical ionospheric plasma parameters are used. As the hydromagnetic waves propagate away from the heated region in the F region, the varying plasma conditions lead to changes in their characteristics. Magnetosonic waves generated in the heating region and propagating down to the E region, where the Hall conductivity is dominant, excite oscillating Hall currents that produce shear Alfvén waves propagating along the field lines into the magnetosphere, where they propagate as the electromagnetic ion cyclotron (EMIC) and whistler waves. The EMIC waves propagate to the ion cyclotron resonance layer in the magnetosphere, where they are absorbed.

  16. Quantification and assessment of heat and cold waves in Novi Sad, Northern Serbia

    Science.gov (United States)

    Basarin, Biljana; Lukić, Tin; Matzarakis, Andreas

    2016-01-01

    Physiologically equivalent temperature (PET) has been applied to the analysis of heat and cold waves and human thermal conditions in Novi Sad, Serbia. A series of daily minimum and maximum air temperature, relative humidity, wind, and cloud cover was used to calculate PET for the investigated period 1949-2012. The heat and cold wave analysis was carried out on days with PET values exceeding defined thresholds. Additionally, the acclimatization approach was introduced to evaluate human adaptation to interannual thermal perception. Trend analysis has revealed the presence of increasing trend in summer PET anomalies, number of days above defined threshold, number of heat waves, and average duration of heat waves per year since 1981. Moreover, winter PET anomaly as well as the number of days below certain threshold and number of cold waves per year until 1980 was decreasing, but the decrease was not statistically significant. The highest number of heat waves during summer was registered in the last two decades, but also in the first decade of the investigated period. On the other hand, the number of cold waves during six decades is quite similar and the differences are very small.

  17. Heat wave probability in the changing climate of the Southwest US

    Science.gov (United States)

    Guirguis, Kristen; Gershunov, Alexander; Cayan, Daniel R.; Pierce, David W.

    2017-09-01

    Analyses of observed non-Gaussian daily minimum and maximum temperature probability distribution functions (PDFs) in the Southwest US highlight the importance of variance and warm tail length in determining future heat wave probability. Even if no PDF shape change occurs with climate change, locations with shorter warm tails and/or smaller variance will see a greater increase in heat wave probability, defined as exceedances above the historical 95th percentile threshold, than will long tailed/larger variance distributions. Projections from ten downscaled CMIP5 models show important geospatial differences in the amount of warming expected for a location. However, changes in heat wave probability do not directly follow changes in background warming. Projected changes in heat wave probability are largely explained by a rigid shift of the daily temperature distribution. In some locations where there is more warming, future heat wave probability is buffered somewhat by longer warm tails. In other parts of the Southwest where there is less warming, heat wave probability is relatively enhanced because of shorter tailed PDFs. Effects of PDF shape changes are generally small by comparison to those from a rigid shift, and fall within the range of uncertainty among models in the amount of warming expected by the end of the century.

  18. Three-wave interaction during electron cyclotron resonance heating and current drive

    DEFF Research Database (Denmark)

    Nielsen, Stefan Kragh; Jacobsen, Asger Schou; Hansen, Søren Kjer

    2016-01-01

    Non-linear wave-wave interactions in fusion plasmas, such as the parametric decay instability (PDI) of gyrotron radiation, can potentially hamper the use of microwave diagnostics. Here we report on anomalous scattering in the ASDEX Upgrade tokamak during electron cyclotron resonance heating...

  19. Anomalous heating of the polar E region by unstable plasma waves. II - Theory

    Science.gov (United States)

    St.-Maurice, J. P.; Schlegel, K.; Banks, P. M.

    1981-01-01

    It is found that anomalous electron temperatures in the disturbed high-latitude E region can be quantitatively explained in terms of heating by unstable plasma waves. The electron temperatures at 110 km have been measured to be as high as 1500 K instead of the expected value of about 300 K. It is shown that by using quasi-linear theory there is an ample source of heat in the unstable waves and that the measured electron temperature profiles have a shape very similar to what is expected from plasma wave heating by the modified two-stream instability. It is found that there is even more heating going to the ion gas, but that the resulting effect on the ion temperature may be difficult to measure. The best estimate of the wave heating rates leads to the conclusion that wave heating can be as much as 50% of the Joule heating for dc electric field strengths of the order of 45 mV/m or greater.

  20. Effects of Simulated Heat Waves with Strong Sudden Cooling Weather on ApoE Knockout Mice

    Science.gov (United States)

    Zhang, Shuyu; Kuang, Zhengzhong; Zhang, Xiakun

    2015-01-01

    This study analyzes the mechanism of influence of heat waves with strong sudden cooling on cardiovascular diseases (CVD) in ApoE−/− mice. The process of heat waves with strong sudden cooling was simulated with a TEM1880 meteorological-environment simulation chamber according to the data obtained at 5 a.m. of 19 June 2006 to 11 p.m. of 22 June 2006. Forty-eight ApoE−/− mice were divided into six blocks based on their weight. Two mice from each block were randomly assigned to control, heat wave, temperature drop, and rewarming temperature groups. The experimental groups were transferred into the climate simulator chamber for exposure to the simulated heat wave process with strong sudden temperature drop. After 55, 59, and 75 h of exposure, the experimental groups were successively removed from the chamber to monitor physiological indicators. Blood samples were collected by decollation, and the hearts were harvested in all groups. The levels of heat stress factors (HSP60, SOD, TNF, sICAM-1, HIF-1α), cold stress factors (NE, EPI), vasoconstrictor factors (ANGII, ET-1, NO), and four items of blood lipid (TC, TG, HDL-C, and LDL-C) were measured in each ApoE−/− mouse. Results showed that the heat waves increased the levels of heat stress factors except SOD decreased, and decreased the levels of vasoconstrictor factors and blood lipid factors except TC increased. The strong sudden temperature drop in the heat wave process increased the levels of cold stress factors, vasoconstrictor factors and four blood lipid items (except the level of HDL-C which decreased) and decreased the levels of heat stress factors (except the level of SOD which increased). The analysis showed that heat waves could enhance atherosclerosis of ApoE−/− mice. The strong sudden temperature drop during the heat wave process increased the plasma concentrations of NE and ANGII, which indicates SNS activation, and resulted in increased blood pressure. NE and ANGII are vasoconstrictors

  1. Heat-Related Mortality in India: Excess All-Cause Mortality Associated with the 2010 Ahmedabad Heat Wave

    Science.gov (United States)

    Azhar, Gulrez Shah; Mavalankar, Dileep; Nori-Sarma, Amruta; Rajiva, Ajit; Dutta, Priya; Jaiswal, Anjali; Sheffield, Perry; Knowlton, Kim; Hess, Jeremy J.; Azhar, Gulrez Shah; Deol, Bhaskar; Bhaskar, Priya Shekhar; Hess, Jeremy; Jaiswal, Anjali; Khosla, Radhika; Knowlton, Kim; Mavalankar, Mavalankar; Rajiva, Ajit; Sarma, Amruta; Sheffield, Perry

    2014-01-01

    Introduction In the recent past, spells of extreme heat associated with appreciable mortality have been documented in developed countries, including North America and Europe. However, far fewer research reports are available from developing countries or specific cities in South Asia. In May 2010, Ahmedabad, India, faced a heat wave where the temperatures reached a high of 46.8°C with an apparent increase in mortality. The purpose of this study is to characterize the heat wave impact and assess the associated excess mortality. Methods We conducted an analysis of all-cause mortality associated with a May 2010 heat wave in Ahmedabad, Gujarat, India, to determine whether extreme heat leads to excess mortality. Counts of all-cause deaths from May 1–31, 2010 were compared with the mean of counts from temporally matched periods in May 2009 and 2011 to calculate excess mortality. Other analyses included a 7-day moving average, mortality rate ratio analysis, and relationship between daily maximum temperature and daily all-cause death counts over the entire year of 2010, using month-wise correlations. Results The May 2010 heat wave was associated with significant excess all-cause mortality. 4,462 all-cause deaths occurred, comprising an excess of 1,344 all-cause deaths, an estimated 43.1% increase when compared to the reference period (3,118 deaths). In monthly pair-wise comparisons for 2010, we found high correlations between mortality and daily maximum temperature during the locally hottest “summer” months of April (r = 0.69, pheat (May 19–25, 2010), mortality rate ratios were 1.76 [95% CI 1.67–1.83, pheat wave in Ahmedabad, Gujarat, India had a substantial effect on all-cause excess mortality, even in this city where hot temperatures prevail through much of April-June. PMID:24633076

  2. Solitary heat waves in nonlinear lattices with squared on-site potential

    Indian Academy of Sciences (India)

    A model Hamiltonian is proposed for heat conduction in a nonlinear lattice with squared on-site potential using the second quantized operators and averaging the same using a suitable wave function, equations are derived in discrete form for the field amplitude and the properties of heat transfer are examined theoretically.

  3. Efficiency at maximum power and efficiency fluctuations in a linear Brownian heat-engine model.

    Science.gov (United States)

    Park, Jong-Min; Chun, Hyun-Myung; Noh, Jae Dong

    2016-07-01

    We investigate the stochastic thermodynamics of a two-particle Langevin system. Each particle is in contact with a heat bath at different temperatures T_{1} and T_{2} (heat engine performing work against the external driving force. Linearity of the system enables us to examine thermodynamic properties of the engine analytically. We find that the efficiency of the engine at maximum power η_{MP} is given by η_{MP}=1-sqrt[T_{2}/T_{1}]. This universal form has been known as a characteristic of endoreversible heat engines. Our result extends the universal behavior of η_{MP} to nonendoreversible engines. We also obtain the large deviation function of the probability distribution for the stochastic efficiency in the overdamped limit. The large deviation function takes the minimum value at macroscopic efficiency η=η[over ¯] and increases monotonically until it reaches plateaus when η≤η_{L} and η≥η_{R} with model-dependent parameters η_{R} and η_{L}.

  4. Efficiency at maximum power and efficiency fluctuations in a linear Brownian heat-engine model

    Science.gov (United States)

    Park, Jong-Min; Chun, Hyun-Myung; Noh, Jae Dong

    2016-07-01

    We investigate the stochastic thermodynamics of a two-particle Langevin system. Each particle is in contact with a heat bath at different temperatures T1 and T2 (autonomous heat engine performing work against the external driving force. Linearity of the system enables us to examine thermodynamic properties of the engine analytically. We find that the efficiency of the engine at maximum power ηM P is given by ηM P=1 -√{T2/T1 } . This universal form has been known as a characteristic of endoreversible heat engines. Our result extends the universal behavior of ηM P to nonendoreversible engines. We also obtain the large deviation function of the probability distribution for the stochastic efficiency in the overdamped limit. The large deviation function takes the minimum value at macroscopic efficiency η =η ¯ and increases monotonically until it reaches plateaus when η ≤ηL and η ≥ηR with model-dependent parameters ηR and ηL.

  5. Researches Regarding the Efficiency of Water to Air Heat Exchanger with Heat Pipes for the Mechanical Ventilation System

    OpenAIRE

    Andrei Burlacu; Theodor Mateescu

    2007-01-01

    The present paper proposes the analysis of the efficiency of water to air heat exchanger with heat pipes for the mechanical ventilation system. The performed study is based on the necessity of the unconventional energy forms capitalization, increasing of the energy efficiency and the energy consumption decrease in concordance with the sustainable development concept.

  6. Researches Regarding the Efficiency of Water to Air Heat Exchanger with Heat Pipes for the Mechanical Ventilation System

    Directory of Open Access Journals (Sweden)

    Andrei Burlacu

    2007-01-01

    Full Text Available The present paper proposes the analysis of the efficiency of water to air heat exchanger with heat pipes for the mechanical ventilation system. The performed study is based on the necessity of the unconventional energy forms capitalization, increasing of the energy efficiency and the energy consumption decrease in concordance with the sustainable development concept.

  7. On the dissipation and dispersion of entropy waves in heat transferring channel flows

    Science.gov (United States)

    Fattahi, A.; Hosseinalipour, S. M.; Karimi, N.

    2017-08-01

    This paper investigates the hydrodynamic and heat transfer effects on the dissipation and dispersion of entropy waves in non-reactive flows. These waves, as advected density inhomogeneities downstream of unsteady flames, may decay partially or totally before reaching the exit nozzle, where they are converted into sound. Attenuation of entropy waves dominates the significance of the subsequent acoustic noise generation. Yet, the extent of this decay process is currently a matter of contention and the pertinent mechanisms are still largely unexplored. To resolve this issue, a numerical study is carried out by compressible large eddy simulation of the wave advection in a channel subject to convective and adiabatic thermal boundary conditions. The dispersion, dissipation, and spatial correlation of the wave are evaluated by post-processing of the numerical results. This includes application of the classical coherence function as well as development of nonlinear quantitative measures of wave dissipation and dispersion. The analyses reveal that the high frequency components of the entropy wave are always strongly damped. The survival of the low frequency components heavily depends on the turbulence intensity and thermal boundary conditions of the channel. In general, high turbulence intensities and particularly heat transfer intensify the decay and destruction of the spatial coherence of entropy waves. In some cases, they can even result in the complete annihilation of the wave. The current work can therefore resolve the controversies arising over the previous studies of entropy waves with different thermal boundary conditions.

  8. Climate variability of heat waves and their associated diurnal temperature range variations in Taiwan

    Science.gov (United States)

    Kueh, M.-T.; Lin, C.-Y.; Chuang, Y.-J.; Sheng, Y.-F.; Chien, Y.-Y.

    2017-07-01

    This study investigates heat waves in Taiwan and their maintenance mechanism, based upon observations and dynamically downscaled simulations. A 95th percentile threshold is used for identifying hot extremes over a period of consecutive days. Heat waves are forecast to become more severe in the future projection. Daily minimum temperatures are generally high and diurnal temperature ranges (DTR) are relatively large. The daily minimum temperature serves as the primary control in the variation in DTR during heat waves. An apparent increase in the daily minimum temperature suggests elevated heat stress at nighttime during future heat waves. Heat waves in Taiwan are associated with abnormal warming and drying atmospheric conditions under the control of an enhanced western North Pacific subtropical high. The surrounding waters serve as a vast moisture source to suppress the drying magnitude in the surface layer as the temperature rises, thereby ensuring a high humidity level during the hot spell. The subsidence and adiabatic warming above can trap the warm and humid air in the surface layer, leading to positive feedback to the abnormally hot surface condition. The associated warming and drying atmospheric conditions cover certain spatial extents, suggesting that the extreme situation identified here is not confined to just an island-wide hot spell; the abnormal hot weather can take place across a broad geographical area.

  9. How hard they hit? Perception, adaptation and public health implications of heat waves in urban and peri-urban Pakistan.

    Science.gov (United States)

    Rauf, Sara; Bakhsh, Khuda; Abbas, Azhar; Hassan, Sarfraz; Ali, Asghar; Kächele, Harald

    2017-04-01

    Heat waves threaten human health given the fast changing climatic scenarios in the recent past. Adaptation to heat waves would take place when people perceive their impacts based on their knowledge. The present study examines perception level and its determinants resulting in adaptation to heat waves in Pakistan. The study used cross-sectional data from urban and peri-urban respondents of Faisalabad District. The study employs a health belief model to assess risk perception among the respondents. Logistic model is used to determine factors affecting level of knowledge, perception and adaptation to heat waves. Around 30% of peri-urban respondents have a low level of knowledge about the fatal impacts of heat waves. Risk perception of heat waves is very low among urban (57%) and peri-urban (66%) respondents. Households' knowledge on heat waves is significantly related to age, gender, education, wealth and access to health services. Determinants of perception include knowledge of heat waves, age and joint effect of marital status and knowledge while income level, family size, urban/peri-urban background, perceived barriers, perceived benefits and cues to action significantly affect adaptation to heat waves. To reduce deadly health impacts, mass awareness campaigns are needed to build perception and improve adaptation to heat waves.

  10. Projection of heat waves over China for eight different global warming targets using 12 CMIP5 models

    Science.gov (United States)

    Guo, Xiaojun; Huang, Jianbin; Luo, Yong; Zhao, Zongci; Xu, Ying

    2017-05-01

    Simulation and projection of the characteristics of heat waves over China were investigated using 12 CMIP5 global climate models and the CN05.1 observational gridded dataset. Four heat wave indices (heat wave frequency, longest heat wave duration, heat wave days, and high temperature days) were adopted in the analysis. Evaluations of the 12 CMIP5 models and their ensemble indicated that the multi-model ensemble could capture the spatiotemporal characteristics of heat wave variation over China. The inter-decadal variations of heat waves during 1961-2005 can be well simulated by multi-model ensemble. Based on model projections, the features of heat waves over China for eight different global warming targets (1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 °C) were explored. The results showed that the frequency and intensity of heat waves would increase more dramatically as the global mean temperature rise attained higher warming targets. Under the RCP8.5 scenario, the four China-averaged heat wave indices would increase from about 1.0 times/year, 2.5, 5.4, and 13.8 days/year to about 3.2 times/year, 14.0, 32.0, and 31.9 days/year for 1.5 and 5.0 °C warming targets, respectively. Those regions that suffer severe heat waves in the base climate would experience the heat waves with greater frequency and severity following global temperature rise. It is also noteworthy that the areas in which a greater number of severe heat waves occur displayed considerable expansion. Moreover, the model uncertainties exhibit a gradual enhancement with projected time extending from 2006 to 2099.

  11. Associations between risk perception, spontaneous adaptation behavior to heat waves and heatstroke in Guangdong province, China.

    Science.gov (United States)

    Liu, Tao; Xu, Yan Jun; Zhang, Yong Hui; Yan, Qing Hua; Song, Xiu Ling; Xie, Hui Yan; Luo, Yuan; Rutherford, Shannon; Chu, Cordia; Lin, Hua Liang; Ma, Wen Jun

    2013-10-02

    In many parts of the world, including in China, extreme heat events or heat waves are likely to increase in intensity, frequency, and duration in light of climate change in the next decades. Risk perception and adaptation behaviors are two important components in reducing the health impacts of heat waves, but little is known about their relationships in China. This study aimed to examine the associations between risk perception to heat waves, adaptation behaviors, and heatstroke among the public in Guangdong province, China. A total of 2,183 adult participants were selected using a four-stage sampling method in Guangdong province. From September to November of 2010 each subject was interviewed at home by a well-trained investigator using a structured questionnaire. The information collected included socio-demographic characteristics, risk perception and spontaneous adaptation behaviors during heat wave periods, and heatstroke experience in the last year. Chi-square tests and unconditional logistic regression models were employed to analyze the data. This study found that 14.8%, 65.3% and 19.9% of participants perceived heat waves as a low, moderate or high health risk, respectively. About 99.1% participants employed at least one spontaneous adaptation behavior, and 26.2%, 51.2% and 22.6% respondents employed 7 adaptation behaviors during heat waves, respectively. Individuals with moderate (OR=2.93, 95% CI: 1.38-6.22) or high (OR=10.58, 95% CI: 4.74-23.63) risk perception experienced more heatstroke in the past year than others. Drinking more water and wearing light clothes in urban areas, while decreasing activity as well as wearing light clothes in rural areas were negatively associated with heatstroke. Individuals with high risk perception and employing risks of heatstroke (OR=47.46, 95% CI: 12.82-175.73). There is a large room for improving health risk perception and adaptation capacity to heat waves among the public of Guangdong province. People with higher

  12. The effects of summer temperature and heat waves on heat-related illness in a coastal city of China, 2011-2013.

    Science.gov (United States)

    Bai, Li; Ding, Gangqiang; Gu, Shaohua; Bi, Peng; Su, Buda; Qin, Dahe; Xu, Guozhang; Liu, Qiyong

    2014-07-01

    Devastating health effects from recent heat waves in China have highlighted the importance of understanding health consequences from extreme heat stress. Despite the increasing mortality from extreme heat, very limited studies have quantified the effects of summer extreme temperature on heat-related illnesses in China. The associations between extreme heat and daily heat-related illnesses that occurred in the summers of 2011-2013 in Ningbo, China, have been examined, using a distributed lag non-linear model (DLNM) based on 3862 cases. The excess morbidities of heat-related illness during each heat wave have been calculated separately and the cumulative heat wave effects on age-, sex-, and cause-specific illnesses in each year along lags have been estimated as well. After controlling the effect of relative humidity, it is found that maximum temperature, rather than heat index, was a better predictor of heat-related illnesses in summers. A positive association between maximum temperatures and occurrence of heat-related diseases was apparent, especially at short lag effects. Six heat waves during the period of 2011-2013 were identified and all associated with excess heat-related illnesses. Relative to the average values for the corresponding periods in 2011 and 2012, a total estimated 679 extra heat-related illnesses occurred during three heat waves in 2013. The significant prolonged heat wave effects on total heat-related illnesses during heat waves in three study years have also been identified. The strongest cumulative effect of heat waves was on severe heat diseases in 2013, with a 10-fold increased risk. More males than females, individuals with more severe forms of illness, were more affected by the heat. However, all age groups were vulnerable. Recent heat waves had a substantial and delayed effect on heat illnesses in Ningbo. Relevant active well-organized public health initiatives should be implemented to reduce the adverse effects of heat extremes on the

  13. Optimal efficiency of a noisy quantum heat engine.

    Science.gov (United States)

    Stefanatos, Dionisis

    2014-07-01

    In this article we use optimal control to maximize the efficiency of a quantum heat engine executing the Otto cycle in the presence of external noise. We optimize the engine performance for both amplitude and phase noise. In the case of phase damping we additionally show that the ideal performance of a noiseless engine can be retrieved in the adiabatic (long time) limit. The results obtained here are useful in the quest for absolute zero, the design of quantum refrigerators that can cool a physical system to the lowest possible temperature. They can also be applied to the optimal control of a collection of classical harmonic oscillators sharing the same time-dependent frequency and subjected to similar noise mechanisms. Finally, our methodology can be used for the optimization of other interesting thermodynamic processes.

  14. Heat-related mortality in India: excess all-cause mortality associated with the 2010 Ahmedabad heat wave.

    Directory of Open Access Journals (Sweden)

    Gulrez Shah Azhar

    Full Text Available INTRODUCTION: In the recent past, spells of extreme heat associated with appreciable mortality have been documented in developed countries, including North America and Europe. However, far fewer research reports are available from developing countries or specific cities in South Asia. In May 2010, Ahmedabad, India, faced a heat wave where the temperatures reached a high of 46.8 °C with an apparent increase in mortality. The purpose of this study is to characterize the heat wave impact and assess the associated excess mortality. METHODS: We conducted an analysis of all-cause mortality associated with a May 2010 heat wave in Ahmedabad, Gujarat, India, to determine whether extreme heat leads to excess mortality. Counts of all-cause deaths from May 1-31, 2010 were compared with the mean of counts from temporally matched periods in May 2009 and 2011 to calculate excess mortality. Other analyses included a 7-day moving average, mortality rate ratio analysis, and relationship between daily maximum temperature and daily all-cause death counts over the entire year of 2010, using month-wise correlations. RESULTS: The May 2010 heat wave was associated with significant excess all-cause mortality. 4,462 all-cause deaths occurred, comprising an excess of 1,344 all-cause deaths, an estimated 43.1% increase when compared to the reference period (3,118 deaths. In monthly pair-wise comparisons for 2010, we found high correlations between mortality and daily maximum temperature during the locally hottest "summer" months of April (r = 0.69, p<0.001, May (r = 0.77, p<0.001, and June (r = 0.39, p<0.05. During a period of more intense heat (May 19-25, 2010, mortality rate ratios were 1.76 [95% CI 1.67-1.83, p<0.001] and 2.12 [95% CI 2.03-2.21] applying reference periods (May 12-18, 2010 from various years. CONCLUSION: The May 2010 heat wave in Ahmedabad, Gujarat, India had a substantial effect on all-cause excess mortality, even in this city where hot temperatures

  15. Mechanism of the Shock Wave Generation and Energy Efficiency by Underwater Discharge

    Directory of Open Access Journals (Sweden)

    O Higa

    2016-09-01

    Full Text Available We are developing the rice powder manufacturing system using an underwater shock wave. The purpose of this study is to research a mechanism of the shock wave generation and energy efficiency by underwater discharge in order to increase energy of the underwater shock wave. We observed the shock wave generation using the visualization device with a high speed camera, and measured voltage current characteristics at the same time. As a result, it was clarified that countless underwater shock waves were generated at the time of water plasma expansion by discharge. But, the shock wave was not confirmed at the time of after a second peak of the damping oscillation. It was clarified that one part of charging energy was used to generation of the shock wave. Therefore, it was clarified that to release energy by the critical oscillation is desirable for efficient generation of the shock wave.

  16. Future changes in Central Europe heat waves expected to mostly follow summer mean warming

    Energy Technology Data Exchange (ETDEWEB)

    Ballester, Joan; Rodo, Xavier [Institut Catala de Ciencies del Clima (IC3), Barcelona, Catalonia (Spain); Giorgi, Filippo [Abdus Salam International Centre for Theoretical Physics, Trieste (Italy)

    2010-12-15

    Daily output from the PRUDENCE ensemble of regional climate simulations for the end of the twentieth and twenty-first centuries over Europe is used to show that the increasing intensity of the most damaging summer heat waves over Central Europe is mostly due to higher base summer temperatures. In this context, base temperature is defined as the mean of the seasonal cycle component for those calendar days when regional heat waves occur and is close, albeit not identical, to the mean temperature for July-August. Although 36-47% of future Central Europe July and August days at the end of the twenty-first century are projected to be extreme according to the present day climatology, specific changes in deseasonalized heat wave anomalies are projected to be relatively small. Instead, changes in summer base temperatures appear much larger, clearly identifiable and of the same order of magnitude as changes in the whole magnitude of heat waves. Our results bear important consequences for the predictability of central European heat wave intensity under global warming conditions. (orig.)

  17. Thermal Conditions in the City of Poznań (Poland during Selected Heat Waves

    Directory of Open Access Journals (Sweden)

    Marek Półrolniczak

    2018-01-01

    Full Text Available The aim of the study was to characterise the occurrence of hot days and heat waves in Poznań in the 1966–2015 period, as well as to describe the thermal conditions in the city during selected heat waves between 2008 and 2015. The basis of the study was the daily maximum and minimum air temperature values for Poznań–Ławica station from 1966–2015 and the daily values of air temperature from eight measuring points located in the city in various land types from 2008 to 2015. A hot day was defined as a day with Tmax above the 95th annual percentile (from 1966 to 2015, while a heat wave was assumed to be at least five consecutive hot days. The research study conducted shows the increase of Tmax, number of hot days and frequency of heat waves in Poznań over the last 50 years. Across the area of the city (differentiation of urban area types according to Urban Atlas 2012, there was a great diversity of thermal conditions during the heat waves analysed.

  18. Monthly and seasonal predictability of heat waves in West Africa with CNRM-CM

    Science.gov (United States)

    Batté, Lauriane; Ardilouze, Constantin; Déqué, Michel

    2017-04-01

    West Africa, and in particular Sahel, are vulnerable to spring heat waves during which maximum daily temperatures reach over 40°C for several consecutive days. These heat waves have severe consequences on the health and activities of local populations. Moreover, several studies suggest that their frequency and intensity may increase in future decades. The French National Research Agency (ANR) project ACASIS brings together researchers from different backgrounds (geography, climate, meteorology, epidemiology, demography) to improve the understanding of the causes and consequences of these heat waves, as well as their variability and predictability at different time and spatial scales. In this presentation we wish to assess the predictability of Sahelian heat waves in the sub-seasonal and seasonal forecasts with Météo-France system 5, based on the CNRM-CM coupled model updated from its CMIP5 version. The seasonal forecasts are issued each month as part of the Copernicus C3S initiative ; sub-seasonal runs are released for research purposes in the framework of the WWRP/WCRP S2S project. Both forecasts are calibrated with corresponding hindcasts over the 1993-2014 period. Despite surface temperature biases, and trouble in properly representing the persistence of heat spells over the region, some evidence of predictive skill is found for duration and frequency of heat waves defined as a threshold of consecutive days of daily minimum or maximum temperatures reaching over the 90th percentile. A more detailed assessment of the spring 2016 real-time forecasts will also be presented, using a weather regime approach to illustrate how the seasonal prediction system managed to capture the large-scale signal for above-normal occurrences and duration of heat waves last year, but failed to correctly pinpoint the geographical location of these anomalies.

  19. The effect of heat waves on ambulance attendances in Brisbane, Australia.

    Science.gov (United States)

    Turner, Lyle R; Connell, Des; Tong, Shilu

    2013-10-01

    Introduction Heat waves have significant impacts on mortality and morbidity. However, little is known regarding effects on pre-admission health outcomes such as ambulance attendances, particularly in subtropical regions. Problem This study investigated both main temperature effects and the added effects of heat waves on ambulance attendances in Brisbane, a subtropical city in Australia. Daily data relating to 783,935 ambulance attendances, along with data on meteorological variables and air pollutants, were collected for the period 2000-2007. Ambient temperature (main) effects were assessed using a distributed lag nonlinear approach that accounted for delayed effects of temperature, while added heat wave effects were incorporated separately using a local heat wave definition. Effect estimates were obtained for total, cardiovascular and respiratory attendances, and different age groups. Main effects of temperature were found for total attendances, which increased by 50.6% (95% CI, 32.3%-71.4%) for a 9.5°C increase above a reference temperature of 29°C. An added heat wave effect on total attendances was observed (18.8%; 95% CI, 6.5%-32.5%). Significant effects were found for both respiratory and cardiovascular attendances, particularly for those aged 65 and above. Ambulance attendances can be significantly impacted by sustained periods of high temperatures, and are a valid source of early detection of the effects of extreme temperatures on the population. The planning of ambulance services may need to be adapted as a consequence of increasing numbers of heat waves in the future. Ambulance attendance data also should be utilized in the development of heat warning systems and climate change adaptation strategies.

  20. Excess mortality during heat waves and cold spells in Moscow, Russia.

    Science.gov (United States)

    Revich, B; Shaposhnikov, D

    2008-10-01

    To estimate excess mortality during heat waves and cold spells, and to identify vulnerable population groups by age and cause of death. Daily mortality in Moscow, Russia from all non-accidental, cardiovascular and respiratory causes between January 2000 and February 2006 was analysed. Mortality and displaced mortality during cold spells and heat waves were estimated using independent samples t tests. Cumulative excess non-accidental mortality during the 2001 heat wave was 33% (95% CI 20% to 46%), or approximately 1200 additional deaths, with short-term displaced mortality contributing about 10% of these. Mortality from coronary heart disease increased by 32% (95% CI 16% to 48%), cerebrovascular mortality by 51% (95% CI 29% to 73%) and respiratory mortality by 80% (95% CI 57% to 101%). In the 75+ age group, corresponding mortality increments were consistently higher except respiratory deaths. An estimated 560 extra deaths were observed during the three heat waves of 2002, when non-accidental mortality increased by 8.5%, 7.8% and 6.1%, respectively. About 40% of these deaths were brought forward by only a few days, bringing net mortality change down to 3.2% (95% CI 0.8% to 5.5%). The cumulative effects of the two cold spells in 2006 on mortality were significant only in the 75+ age group, for which average daily mortality from all non-accidental causes increased by 9.9% (95% CI 8.0% to 12%) and 8.9% (95% CI 6.7% to 11%), resulting in 370 extra deaths; there were also significant increases in coronary disease mortality and cerebrovascular mortality. This study confirms that daily mortality in Moscow increases during heat waves and cold spells. A considerable proportion of excess deaths during heat waves occur a short time earlier than they would otherwise have done. Harvesting, or short-term mortality displacement, may be less significant for longer periods of sustained heat stress.

  1. Efficient generation of energetic ions in multi-ion plasmas by radio-frequency heating

    Science.gov (United States)

    Kazakov, Ye. O.; Ongena, J.; Wright, J. C.; Wukitch, S. J.; Lerche, E.; Mantsinen, M. J.; van Eester, D.; Craciunescu, T.; Kiptily, V. G.; Lin, Y.; Nocente, M.; Nabais, F.; Nave, M. F. F.; Baranov, Y.; Bielecki, J.; Bilato, R.; Bobkov, V.; Crombé, K.; Czarnecka, A.; Faustin, J. M.; Felton, R.; Fitzgerald, M.; Gallart, D.; Giacomelli, L.; Golfinopoulos, T.; Hubbard, A. E.; Jacquet, Ph.; Johnson, T.; Lennholm, M.; Loarer, T.; Porkolab, M.; Sharapov, S. E.; Valcarcel, D.; van Schoor, M.; Weisen, H.; Marmar, E. S.; Baek, S. G.; Barnard, H.; Bonoli, P.; Brunner, D.; Candy, J.; Canik, J.; Churchill, R. M.; Cziegler, I.; Dekow, G.; Delgado-Aparicio, L.; Diallo, A.; Edlund, E.; Ennever, P.; Faust, I.; Fiore, C.; Gao, Chi; Golfinopoulos, T.; Greenwald, M.; Hartwig, Z. S.; Holland, C.; Hubbard, A. E.; Hughes, J. W.; Hutchinson, I. H.; Irby, J.; Labombard, B.; Lin, Yijun; Lipschultz, B.; Loarte, A.; Mumgaard, R.; Parker, R. R.; Porkolab, M.; Reinke, M. L.; Rice, J. E.; Scott, S.; Shiraiwa, S.; Snyder, P.; Sorbom, B.; Terry, D.; Terry, J. L.; Theiler, C.; Vieira, R.; Walk, J. R.; Wallace, G. M.; White, A.; Whyte, D.; Wolfe, S. M.; Wright, G. M.; Wright, J.; Wukitch, S. J.; Xu, P.; Abduallev, S.; Abhangi, M.; Abreu, P.; Afzal, M.; Aggarwal, K. M.; Ahlgren, T.; Ahn, J. H.; Aho-Mantila, L.; Aiba, N.; Airila, M.; Albanese, R.; Aldred, V.; Alegre, D.; Alessi, E.; Aleynikov, P.; Alfier, A.; Alkseev, A.; Allinson, M.; Alper, B.; Alves, E.; Ambrosino, G.; Ambrosino, R.; Amicucci, L.; Amosov, V.; Sundén, E. Andersson; Angelone, M.; Anghel, M.; Angioni, C.; Appel, L.; Appelbee, C.; Arena, P.; Ariola, M.; Arnichand, H.; Arshad, S.; Ash, A.; Ashikawa, N.; Aslanyan, V.; Asunta, O.; Auriemma, F.; Austin, Y.; Avotina, L.; Axton, M. D.; Ayres, C.; Bacharis, M.; Baciero, A.; Baião, D.; Bailey, S.; Baker, A.; Balboa, I.; Balden, M.; Balshaw, N.; Bament, R.; Banks, J. W.; Baranov, Y. F.; Barnard, M. A.; Barnes, D.; Barnes, M.; Barnsley, R.; Wiechec, A. Baron; Orte, L. Barrera; Baruzzo, M.; Basiuk, V.; Bassan, M.; Bastow, R.; Batista, A.; Batistoni, P.; Baughan, R.; Bauvir, B.; Baylor, L.; Bazylev, B.; Beal, J.; Beaumont, P. S.; Beckers, M.; Beckett, B.; Becoulet, A.; Bekris, N.; Beldishevski, M.; Bell, K.; Belli, F.; Bellinger, M.; Belonohy, É.; Ayed, N. Ben; Benterman, N. A.; Bergsåker, H.; Bernardo, J.; Bernert, M.; Berry, M.; Bertalot, L.; Besliu, C.; Beurskens, M.; Bieg, B.; Bielecki, J.; Biewer, T.; Bigi, M.; Bílková, P.; Binda, F.; Bisoffi, A.; Bizarro, J. P. S.; Björkas, C.; Blackburn, J.; Blackman, K.; Blackman, T. R.; Blanchard, P.; Blatchford, P.; Bobkov, V.; Boboc, A.; Bodnár, G.; Bogar, O.; Bolshakova, I.; Bolzonella, T.; Bonanomi, N.; Bonelli, F.; Boom, J.; Booth, J.; Borba, D.; Borodin, D.; Borodkina, I.; Botrugno, A.; Bottereau, C.; Boulting, P.; Bourdelle, C.; Bowden, M.; Bower, C.; Bowman, C.; Boyce, T.; Boyd, C.; Boyer, H. J.; Bradshaw, J. M. A.; Braic, V.; Bravanec, R.; Breizman, B.; Bremond, S.; Brennan, P. D.; Breton, S.; Brett, A.; Brezinsek, S.; Bright, M. D. J.; Brix, M.; Broeckx, W.; Brombin, M.; Brosławski, A.; Brown, D. P. D.; Brown, M.; Bruno, E.; Bucalossi, J.; Buch, J.; Buchanan, J.; Buckley, M. A.; Budny, R.; Bufferand, H.; Bulman, M.; Bulmer, N.; Bunting, P.; Buratti, P.; Burckhart, A.; Buscarino, A.; Busse, A.; Butler, N. K.; Bykov, I.; Byrne, J.; Cahyna, P.; Calabrò, G.; Calvo, I.; Camenen, Y.; Camp, P.; Campling, D. C.; Cane, J.; Cannas, B.; Capel, A. J.; Card, P. J.; Cardinali, A.; Carman, P.; Carr, M.; Carralero, D.; Carraro, L.; Carvalho, B. B.; Carvalho, I.; Carvalho, P.; Casson, F. J.; Castaldo, C.; Catarino, N.; Caumont, J.; Causa, F.; Cavazzana, R.; Cave-Ayland, K.; Cavinato, M.; Cecconello, M.; Ceccuzzi, S.; Cecil, E.; Cenedese, A.; Cesario, R.; Challis, C. D.; Chandler, M.; Chandra, D.; Chang, C. S.; Chankin, A.; Chapman, I. T.; Chapman, S. C.; Chernyshova, M.; Chitarin, G.; Ciraolo, G.; Ciric, D.; Citrin, J.; Clairet, F.; Clark, E.; Clark, M.; Clarkson, R.; Clatworthy, D.; Clements, C.; Cleverly, M.; Coad, J. P.; Coates, P. A.; Cobalt, A.; Coccorese, V.; Cocilovo, V.; Coda, S.; Coelho, R.; Coenen, J. W.; Coffey, I.; Colas, L.; Collins, S.; Conka, D.; Conroy, S.; Conway, N.; Coombs, D.; Cooper, D.; Cooper, S. R.; Corradino, C.; Corre, Y.; Corrigan, G.; Cortes, S.; Coster, D.; Couchman, A. S.; Cox, M. P.; Craciunescu, T.; Cramp, S.; Craven, R.; Crisanti, F.; Croci, G.; Croft, D.; Crombé, K.; Crowe, R.; Cruz, N.; Cseh, G.; Cufar, A.; Cullen, A.; Curuia, M.; Czarnecka, A.; Dabirikhah, H.; Dalgliesh, P.; Dalley, S.; Dankowski, J.; Darrow, D.; Davies, O.; Davis, W.; Day, C.; Day, I. E.; de Bock, M.; de Castro, A.; de La Cal, E.; de La Luna, E.; Masi, G. De; de Pablos, J. L.; de Temmerman, G.; de Tommasi, G.; de Vries, P.; Deakin, K.; Deane, J.; Agostini, F. Degli; Dejarnac, R.; Delabie, E.; den Harder, N.; Dendy, R. O.; Denis, J.; Denner, P.; Devaux, S.; Devynck, P.; Maio, F. Di; Siena, A. Di; Troia, C. Di; Dinca, P.; D'Inca, R.; Ding, B.; Dittmar, T.; Doerk, H.; Doerner, R. P.; Donné, T.; Dorling, S. E.; Dormido-Canto, S.; Doswon, S.; Douai, D.; Doyle, P. T.; Drenik, A.; Drewelow, P.; Drews, P.; Duckworth, Ph.; Dumont, R.; Dumortier, P.; Dunai, D.; Dunne, M.; Ďuran, I.; Durodié, F.; Dutta, P.; Duval, B. P.; Dux, R.; Dylst, K.; Dzysiuk, N.; Edappala, P. V.; Edmond, J.; Edwards, A. M.; Edwards, J.; Eich, Th.; Ekedahl, A.; El-Jorf, R.; Elsmore, C. G.; Enachescu, M.; Ericsson, G.; Eriksson, F.; Eriksson, J.; Eriksson, L. G.; Esposito, B.; Esquembri, S.; Esser, H. G.; Esteve, D.; Evans, B.; Evans, G. E.; Evison, G.; Ewart, G. D.; Fagan, D.; Faitsch, M.; Falie, D.; Fanni, A.; Fasoli, A.; Faustin, J. M.; Fawlk, N.; Fazendeiro, L.; Fedorczak, N.; Felton, R. C.; Fenton, K.; Fernades, A.; Fernandes, H.; Ferreira, J.; Fessey, J. A.; Février, O.; Ficker, O.; Field, A.; Fietz, S.; Figueiredo, A.; Figueiredo, J.; Fil, A.; Finburg, P.; Firdaouss, M.; Fischer, U.; Fittill, L.; Fitzgerald, M.; Flammini, D.; Flanagan, J.; Fleming, C.; Flinders, K.; Fonnesu, N.; Fontdecaba, J. M.; Formisano, A.; Forsythe, L.; Fortuna, L.; Fortuna-Zalesna, E.; Fortune, M.; Foster, S.; Franke, T.; Franklin, T.; Frasca, M.; Frassinetti, L.; Freisinger, M.; Fresa, R.; Frigione, D.; Fuchs, V.; Fuller, D.; Futatani, S.; Fyvie, J.; Gál, K.; Galassi, D.; Gałązka, K.; Galdon-Quiroga, J.; Gallagher, J.; Gallart, D.; Galvão, R.; Gao, X.; Gao, Y.; Garcia, J.; Garcia-Carrasco, A.; García-Muñoz, M.; Gardarein, J.-L.; Garzotti, L.; Gaudio, P.; Gauthier, E.; Gear, D. F.; Gee, S. J.; Geiger, B.; Gelfusa, M.; Gerasimov, S.; Gervasini, G.; Gethins, M.; Ghani, Z.; Ghate, M.; Gherendi, M.; Giacalone, J. C.; Giacomelli, L.; Gibson, C. S.; Giegerich, T.; Gil, C.; Gil, L.; Gilligan, S.; Gin, D.; Giovannozzi, E.; Girardo, J. B.; Giroud, C.; Giruzzi, G.; Glöggler, S.; Godwin, J.; Goff, J.; Gohil, P.; Goloborod'Ko, V.; Gomes, R.; Gonçalves, B.; Goniche, M.; Goodliffe, M.; Goodyear, A.; Gorini, G.; Gosk, M.; Goulding, R.; Goussarov, A.; Gowland, R.; Graham, B.; Graham, M. E.; Graves, J. P.; Grazier, N.; Grazier, P.; Green, N. R.; Greuner, H.; Grierson, B.; Griph, F. S.; Grisolia, C.; Grist, D.; Groth, M.; Grove, R.; Grundy, C. N.; Grzonka, J.; Guard, D.; Guérard, C.; Guillemaut, C.; Guirlet, R.; Gurl, C.; Utoh, H. H.; Hackett, L. J.; Hacquin, S.; Hagar, A.; Hager, R.; Hakola, A.; Halitovs, M.; Hall, S. J.; Cook, S. P. Hallworth; Hamlyn-Harris, C.; Hammond, K.; Harrington, C.; Harrison, J.; Harting, D.; Hasenbeck, F.; Hatano, Y.; Hatch, D. R.; Haupt, T. D. V.; Hawes, J.; Hawkes, N. C.; Hawkins, J.; Hawkins, P.; Haydon, P. W.; Hayter, N.; Hazel, S.; Heesterman, P. J. L.; Heinola, K.; Hellesen, C.; Hellsten, T.; Helou, W.; Hemming, O. N.; Hender, T. C.; Henderson, M.; Henderson, S. S.; Henriques, R.; Hepple, D.; Hermon, G.; Hertout, P.; Hidalgo, C.; Highcock, E. G.; Hill, M.; Hillairet, J.; Hillesheim, J.; Hillis, D.; Hizanidis, K.; Hjalmarsson, A.; Hobirk, J.; Hodille, E.; Hogben, C. H. A.; Hogeweij, G. M. D.; Hollingsworth, A.; Hollis, S.; Homfray, D. A.; Horáček, J.; Hornung, G.; Horton, A. R.; Horton, L. D.; Horvath, L.; Hotchin, S. P.; Hough, M. R.; Howarth, P. J.; Hubbard, A.; Huber, A.; Huber, V.; Huddleston, T. M.; Hughes, M.; Huijsmans, G. T. A.; Hunter, C. L.; Huynh, P.; Hynes, A. M.; Iglesias, D.; Imazawa, N.; Imbeaux, F.; Imríšek, M.; Incelli, M.; Innocente, P.; Irishkin, M.; Ivanova-Stanik, I.; Jachmich, S.; Jacobsen, A. S.; Jacquet, P.; Jansons, J.; Jardin, A.; Järvinen, A.; Jaulmes, F.; Jednoróg, S.; Jenkins, I.; Jeong, C.; Jepu, I.; Joffrin, E.; Johnson, R.; Johnson, T.; Johnston, Jane; Joita, L.; Jones, G.; Jones, T. T. C.; Hoshino, K. K.; Kallenbach, A.; Kamiya, K.; Kaniewski, J.; Kantor, A.; Kappatou, A.; Karhunen, J.; Karkinsky, D.; Karnowska, I.; Kaufman, M.; Kaveney, G.; Kazakov, Y.; Kazantzidis, V.; Keeling, D. L.; Keenan, T.; Keep, J.; Kempenaars, M.; Kennedy, C.; Kenny, D.; Kent, J.; Kent, O. N.; Khilkevich, E.; Kim, H. T.; Kim, H. S.; Kinch, A.; King, C.; King, D.; King, R. F.; Kinna, D. J.; Kiptily, V.; Kirk, A.; Kirov, K.; Kirschner, A.; Kizane, G.; Klepper, C.; Klix, A.; Knight, P.; Knipe, S. J.; Knott, S.; Kobuchi, T.; Köchl, F.; Kocsis, G.; Kodeli, I.; Kogan, L.; Kogut, D.; Koivuranta, S.; Kominis, Y.; Köppen, M.; Kos, B.; Koskela, T.; Koslowski, H. R.; Koubiti, M.; Kovari, M.; Kowalska-Strzęciwilk, E.; Krasilnikov, A.; Krasilnikov, V.; Krawczyk, N.; Kresina, M.; Krieger, K.; Krivska, A.; Kruezi, U.; Książek, I.; Kukushkin, A.; Kundu, A.; Kurki-Suonio, T.; Kwak, S.; Kwiatkowski, R.; Kwon, O. J.; Laguardia, L.; Lahtinen, A.; Laing, A.; Lam, N.; Lambertz, H. T.; Lane, C.; Lang, P. T.; Lanthaler, S.; Lapins, J.; Lasa, A.; Last, J. R.; Łaszyńska, E.; Lawless, R.; Lawson, A.; Lawson, K. D.; Lazaros, A.; Lazzaro, E.; Leddy, J.; Lee, S.; Lefebvre, X.; Leggate, H. J.; Lehmann, J.; Lehnen, M.; Leichtle, D.; Leichuer, P.; Leipold, F.; Lengar, I.; Lennholm, M.; Lerche, E.; Lescinskis, A.; Lesnoj, S.; Letellier, E.; Leyland, M.; Leysen, W.; Li, L.; Liang, Y.; Likonen, J.; Linke, J.; Linsmeier, Ch.; Lipschultz, B.; Litaudon, X.; Liu, G.; Liu, Y.; Lo Schiavo, V. P.; Loarer, T.; Loarte, A.; Lobel, R. C.; Lomanowski, B.; Lomas, P. J.; Lönnroth, J.; López, J. M.; López-Razola, J.; Lorenzini, R.; Losada, U.; Lovell, J. J.; Loving, A. B.; Lowry, C.; Luce, T.; Lucock, R. M. A.; Lukin, A.; Luna, C.; Lungaroni, M.; Lungu, C. P.; Lungu, M.; Lunniss, A.; Lupelli, I.; Lyssoivan, A.; MacDonald, N.; Macheta, P.; Maczewa, K.; Magesh, B.; Maget, P.; Maggi, C.; Maier, H.; Mailloux, J.; Makkonen, T.; Makwana, R.; Malaquias, A.; Malizia, A.; Manas, P.; Manning, A.; Manso, M. E.; Mantica, P.; Mantsinen, M.; Manzanares, A.; Maquet, Ph.; Marandet, Y.; Marcenko, N.; Marchetto, C.; Marchuk, O.; Marinelli, M.; Marinucci, M.; Markovič, T.; Marocco, D.; Marot, L.; Marren, C. A.; Marshal, R.; Martin, A.; Martin, Y.; Martín de Aguilera, A.; Martínez, F. J.; Martín-Solís, J. R.; Martynova, Y.; Maruyama, S.; Masiello, A.; Maslov, M.; Matejcik, S.; Mattei, M.; Matthews, G. F.; Maviglia, F.; Mayer, M.; Mayoral, M. L.; May-Smith, T.; Mazon, D.; Mazzotta, C.; McAdams, R.; McCarthy, P. J.; McClements, K. G.; McCormack, O.; McCullen, P. A.; McDonald, D.; McIntosh, S.; McKean, R.; McKehon, J.; Meadows, R. C.; Meakins, A.; Medina, F.; Medland, M.; Medley, S.; Meigh, S.; Meigs, A. G.; Meisl, G.; Meitner, S.; Meneses, L.; Menmuir, S.; Mergia, K.; Merrigan, I. R.; Mertens, Ph.; Meshchaninov, S.; Messiaen, A.; Meyer, H.; Mianowski, S.; Michling, R.; Middleton-Gear, D.; Miettunen, J.; Militello, F.; Militello-Asp, E.; Miloshevsky, G.; Mink, F.; Minucci, S.; Miyoshi, Y.; Mlynář, J.; Molina, D.; Monakhov, I.; Moneti, M.; Mooney, R.; Moradi, S.; Mordijck, S.; Moreira, L.; Moreno, R.; Moro, F.; Morris, A. W.; Morris, J.; Moser, L.; Mosher, S.; Moulton, D.; Murari, A.; Muraro, A.; Murphy, S.; Asakura, N. N.; Na, Y. S.; Nabais, F.; Naish, R.; Nakano, T.; Nardon, E.; Naulin, V.; Nave, M. F. F.; Nedzelski, I.; Nemtsev, G.; Nespoli, F.; Neto, A.; Neu, R.; Neverov, V. S.; Newman, M.; Nicholls, K. J.; Nicolas, T.; Nielsen, A. H.; Nielsen, P.; Nilsson, E.; Nishijima, D.; Noble, C.; Nocente, M.; Nodwell, D.; Nordlund, K.; Nordman, H.; Nouailletas, R.; Nunes, I.; Oberkofler, M.; Odupitan, T.; Ogawa, M. T.; O'Gorman, T.; Okabayashi, M.; Olney, R.; Omolayo, O.; O'Mullane, M.; Ongena, J.; Orsitto, F.; Orszagh, J.; Oswuigwe, B. I.; Otin, R.; Owen, A.; Paccagnella, R.; Pace, N.; Pacella, D.; Packer, L. W.; Page, A.; Pajuste, E.; Palazzo, S.; Pamela, S.; Panja, S.; Papp, P.; Paprok, R.; Parail, V.; Park, M.; Diaz, F. Parra; Parsons, M.; Pasqualotto, R.; Patel, A.; Pathak, S.; Paton, D.; Patten, H.; Pau, A.; Pawelec, E.; Soldan, C. Paz; Peackoc, A.; Pearson, I. J.; Pehkonen, S.-P.; Peluso, E.; Penot, C.; Pereira, A.; Pereira, R.; Puglia, P. P. Pereira; von Thun, C. Perez; Peruzzo, S.; Peschanyi, S.; Peterka, M.; Petersson, P.; Petravich, G.; Petre, A.; Petrella, N.; Petržilka, V.; Peysson, Y.; Pfefferlé, D.; Philipps, V.; Pillon, M.; Pintsuk, G.; Piovesan, P.; Dos Reis, A. Pires; Piron, L.; Pironti, A.; Pisano; Pitts, R.; Pizzo, F.; Plyusnin, V.; Pomaro, N.; Pompilian, O. G.; Pool, P. J.; Popovichev, S.; Porfiri, M. T.; Porosnicu, C.; Porton, M.; Possnert, G.; Potzel, S.; Powell, T.; Pozzi, J.; Prajapati, V.; Prakash, R.; Prestopino, G.; Price, D.; Price, M.; Price, R.; Prior, P.; Proudfoot, R.; Pucella, G.; Puglia, P.; Puiatti, M. E.; Pulley, D.; Purahoo, K.; Pütterich, Th.; Rachlew, E.; Rack, M.; Ragona, R.; Rainford, M. S. J.; Rakha, A.; Ramogida, G.; Ranjan, S.; Rapson, C. J.; Rasmussen, J. J.; Rathod, K.; Rattá, G.; Ratynskaia, S.; Ravera, G.; Rayner, C.; Rebai, M.; Reece, D.; Reed, A.; Réfy, D.; Regan, B.; Regaña, J.; Reich, M.; Reid, N.; Reimold, F.; Reinhart, M.; Reinke, M.; Reiser, D.; Rendell, D.; Reux, C.; Cortes, S. D. A. Reyes; Reynolds, S.; Riccardo, V.; Richardson, N.; Riddle, K.; Rigamonti, D.; Rimini, F. G.; Risner, J.; Riva, M.; Roach, C.; Robins, R. J.; Robinson, S. A.; Robinson, T.; Robson, D. W.; Roccella, R.; Rodionov, R.; Rodrigues, P.; Rodriguez, J.; Rohde, V.; Romanelli, F.; Romanelli, M.; Romanelli, S.; Romazanov, J.; Rowe, S.; Rubel, M.; Rubinacci, G.; Rubino, G.; Ruchko, L.; Ruiz, M.; Ruset, C.; Rzadkiewicz, J.; Saarelma, S.; Sabot, R.; Safi, E.; Sagar, P.; Saibene, G.; Saint-Laurent, F.; Salewski, M.; Salmi, A.; Salmon, R.; Salzedas, F.; Samaddar, D.; Samm, U.; Sandiford, D.; Santa, P.; Santala, M. I. K.; Santos, B.; Santucci, A.; Sartori, F.; Sartori, R.; Sauter, O.; Scannell, R.; Schlummer, T.; Schmid, K.; Schmidt, V.; Schmuck, S.; Schneider, M.; Schöpf, K.; Schwörer, D.; Scott, S. D.; Sergienko, G.; Sertoli, M.; Shabbir, A.; Sharapov, S. E.; Shaw, A.; Shaw, R.; Sheikh, H.; Shepherd, A.; Shevelev, A.; Shumack, A.; Sias, G.; Sibbald, M.; Sieglin, B.; Silburn, S.; Silva, A.; Silva, C.; Simmons, P. A.; Simpson, J.; Simpson-Hutchinson, J.; Sinha, A.; Sipilä, S. K.; Sips, A. C. C.; Sirén, P.; Sirinelli, A.; Sjöstrand, H.; Skiba, M.; Skilton, R.; Slabkowska, K.; Slade, B.; Smith, N.; Smith, P. G.; Smith, R.; Smith, T. J.; Smithies, M.; Snoj, L.; Soare, S.; Solano, E. R.; Somers, A.; Sommariva, C.; Sonato, P.; Sopplesa, A.; Sousa, J.; Sozzi, C.; Spagnolo, S.; Spelzini, T.; Spineanu, F.; Stables, G.; Stamatelatos, I.; Stamp, M. F.; Staniec, P.; Stankūnas, G.; Stan-Sion, C.; Stead, M. J.; Stefanikova, E.; Stepanov, I.; Stephen, A. V.; Stephen, M.; Stevens, A.; Stevens, B. D.; Strachan, J.; Strand, P.; Strauss, H. R.; Ström, P.; Stubbs, G.; Studholme, W.; Subba, F.; Summers, H. P.; Svensson, J.; Świderski, Ł.; Szabolics, T.; Szawlowski, M.; Szepesi, G.; Suzuki, T. T.; Tál, B.; Tala, T.; Talbot, A. R.; Talebzadeh, S.; Taliercio, C.; Tamain, P.; Tame, C.; Tang, W.; Tardocchi, M.; Taroni, L.; Taylor, D.; Taylor, K. A.; Tegnered, D.; Telesca, G.; Teplova, N.; Terranova, D.; Testa, D.; Tholerus, E.; Thomas, J.; Thomas, J. D.; Thomas, P.; Thompson, A.; Thompson, C.-A.; Thompson, V. K.; Thorne, L.; Thornton, A.; Thrysøe, A. S.; Tigwell, P. A.; Tipton, N.; Tiseanu, I.; Tojo, H.; Tokitani, M.; Tolias, P.; Tomeš, M.; Tonner, P.; Towndrow, M.; Trimble, P.; Tripsky, M.; Tsalas, M.; Tsavalas, P.; Jun, D. Tskhakaya; Turner, I.; Turner, M. M.; Turnyanskiy, M.; Tvalashvili, G.; Tyrrell, S. G. J.; Uccello, A.; Ul-Abidin, Z.; Uljanovs, J.; Ulyatt, D.; Urano, H.; Uytdenhouwen, I.; Vadgama, A. P.; Valcarcel, D.; Valentinuzzi, M.; Valisa, M.; Olivares, P. Vallejos; Valovic, M.; van de Mortel, M.; van Eester, D.; van Renterghem, W.; van Rooij, G. J.; Varje, J.; Varoutis, S.; Vartanian, S.; Vasava, K.; Vasilopoulou, T.; Vega, J.; Verdoolaege, G.; Verhoeven, R.; Verona, C.; Rinati, G. Verona; Veshchev, E.; Vianello, N.; Vicente, J.; Viezzer, E.; Villari, S.; Villone, F.; Vincenzi, P.; Vinyar, I.; Viola, B.; Vitins, A.; Vizvary, Z.; Vlad, M.; Voitsekhovitch, I.; Vondráček, P.; Vora, N.; Vu, T.; de Sa, W. W. Pires; Wakeling, B.; Waldon, C. W. F.; Walkden, N.; Walker, M.; Walker, R.; Walsh, M.; Wang, E.; Wang, N.; Warder, S.; Warren, R. J.; Waterhouse, J.; Watkins, N. W.; Watts, C.; Wauters, T.; Weckmann, A.; Weiland, J.; Weisen, H.; Weiszflog, M.; Wellstood, C.; West, A. T.; Wheatley, M. R.; Whetham, S.; Whitehead, A. M.; Whitehead, B. D.; Widdowson, A. M.; Wiesen, S.; Wilkinson, J.; Williams, J.; Williams, M.; Wilson, A. R.; Wilson, D. J.; Wilson, H. R.; Wilson, J.; Wischmeier, M.; Withenshaw, G.; Withycombe, A.; Witts, D. M.; Wood, D.; Wood, R.; Woodley, C.; Wray, S.; Wright, J.; Wright, J. C.; Wu, J.; Wukitch, S.; Wynn, A.; Xu, T.; Yadikin, D.; Yanling, W.; Yao, L.; Yavorskij, V.; Yoo, M. G.; Young, C.; Young, D.; Young, I. D.; Young, R.; Zacks, J.; Zagorski, R.; Zaitsev, F. S.; Zanino, R.; Zarins, A.; Zastrow, K. D.; Zerbini, M.; Zhang, W.; Zhou, Y.; Zilli, E.; Zoita, V.; Zoletnik, S.; Zychor, I.

    2017-10-01

    We describe a new technique for the efficient generation of high-energy ions with electromagnetic ion cyclotron waves in multi-ion plasmas. The discussed `three-ion' scenarios are especially suited for strong wave absorption by a very low number of resonant ions. To observe this effect, the plasma composition has to be properly adjusted, as prescribed by theory. We demonstrate the potential of the method on the world-largest plasma magnetic confinement device, JET (Joint European Torus, Culham, UK), and the high-magnetic-field tokamak Alcator C-Mod (Cambridge, USA). The obtained results demonstrate efficient acceleration of 3He ions to high energies in dedicated hydrogen-deuterium mixtures. Simultaneously, effective plasma heating is observed, as a result of the slowing-down of the fast 3He ions. The developed technique is not only limited to laboratory plasmas, but can also be applied to explain observations of energetic ions in space-plasma environments, in particular, 3He-rich solar flares.

  2. Vertical elliptic operator for efficient wave propagation in TTI media

    KAUST Repository

    Waheed, Umair bin

    2015-08-19

    Elliptic wave extrapolation operators require significantly less computational cost than the ones for transversely isotropic (TI) media. However, it does not provide accurate wavefield representation or imaging for the prevalent TI media. We propose a new vertical elliptically anisotropic (VEA) wave equation by decomposing the acoustic TI pseudo-differential wave equation. The decomposition results in a vertical elliptic differential equation and a scalar operator. The new VEA-like wave equation shares the same dispersion relation as that of the original acoustic TI wave equation. Therefore, the kinematic contents are correctly matched to the original equation. Moreover, the proposed decomposition yields better amplitude properties than the isotropic decomposition without increasing the computational load. Therefore, it exhibits better cost versus accuracy tradeoff compared to the isotropic or the tilted elliptic decompositions. We demonstrate with numerical examples that the proposed methodology is numerically stable for complex models and is free from shear-wave artifacts.

  3. Propagation of waves in a gravitating and rotating anisotropic heat ...

    African Journals Online (AJOL)

    Bheema

    propagations become anti-symmetric. It is illustrated that the phase speed of the forward propagating mode increases with increasing drift and the backward propagating mode decreases with increasing drift. In this particular direction of propagation and axis of rotation, this wave mode is also independent of rotation ...

  4. Influence of Compressor Station Waste-Heat Recovery Section on Operational Efficiency of Gas Turbine Drive with Isobaric Heat Supply and Regenerative Heat Utilization

    Directory of Open Access Journals (Sweden)

    A. P. Nesenchuk

    2013-01-01

    Full Text Available The possibility to utilize existing secondary energy resources for heat supply of an industrial enterprise has been proposed on the basis of the analysis on operation of compressor stations of a cross-country gas pipe-line. The paper considers an influence of waste heat recovery section on operational efficiency of gas turbine drive with regenerative heat utilization.

  5. Analyses of thermoregulatory responses of feeder cattle exposed to simulated heat waves.

    Science.gov (United States)

    Brown-Brandl, T M; Eigenberg, R A; Hahn, G L; Nienaber, J A; Mader, T L; Spiers, D E; Parkhurst, A M

    2005-05-01

    Heat stress in feedlot cattle causes reduced performance, and in the most severe cases, death of the animals, thus causing the loss of millions of dollars in revenue to the cattle industry. A study was designed to evaluate dynamics of thermoregulation and feeding activities when feeder cattle were exposed to simulated heat waves, in comparison with repeated sinusoidal hot and thermoneutral environments. Nine beef steers were randomly assigned to an individual pen in one of three environmental chambers. Each chamber was subjected to each of three temperature regimes (heatwave simulation from Rockport, Mo., 1995, heatwave simulation from Columbia, Mo., 1999, and Controlled heat stress treatment of 32+/-7 degrees C) for a period of 18 days, according to a Latin square treatment design, with a 10-day thermoneutral period (18+/-7 degrees C) separating treatment periods. Respiration rate, core body temperature, heat production, feed intake, and feeding behavior were measured on each animal for the duration of the experiment. Differences were found in all treatments for all parameters except feeding behavior. It was shown that the two simulated heat waves elicited very different thermoregulatory responses. Based on these results the heat wave centered at Rockport, Mo. in 1995 was devastating because the animals were not acclimated to hot conditions, thus causing an acute response to heat stress. The responses of cattle to conditions at Columbia, Mo. showed some acclimation to heat prior to the peak stress days, and therefore a dampened response was seen. It appears the extreme conditions at Columbia, Mo., 1999 were made severe by environmental conditions not simulated during this study (low wind speed and intensive solar radiation). Overall, it was determined while a cyclic heat stress treatment is a representative model to test heat stress in cattle, further heat stress experiments should be conducted in an actual feedlot.

  6. Analyses of thermoregulatory responses of feeder cattle exposed to simulated heat waves

    Science.gov (United States)

    Brown-Brandl, T. M.; Eigenberg, R. A.; Hahn, G. L.; Nienaber, J. A.; Mader, T. L.; Spiers, D. E.; Parkhurst, A. M.

    2005-05-01

    Heat stress in feedlot cattle causes reduced performance, and in the most severe cases, death of the animals, thus causing the loss of millions of dollars in revenue to the cattle industry. A study was designed to evaluate dynamics of thermoregulation and feeding activities when feeder cattle were exposed to simulated heat waves, in comparison with repeated sinusoidal hot and thermoneutral environments. Nine beef steers were randomly assigned to an individual pen in one of three environmental chambers. Each chamber was subjected to each of three temperature regimes (Heatwave simulation from Rockport, Mo., 1995, Heatwave simulation from Columbia, Mo., 1999, and Controlled heat stress treatment of 32±7°C) for a period of 18 days, according to a Latin square treatment design, with a 10-day thermoneutral period (18±7°C) separating treatment periods. Respiration rate, core body temperature, heat production, feed intake, and feeding behavior were measured on each animal for the duration of the experiment. Differences were found in all treatments for all parameters except feeding behavior. It was shown that the two simulated heat waves elicited very different thermoregulatory responses. Based on these results the heat wave centered at Rockport, Mo. in 1995 was devastating because the animals were not acclimated to hot conditions, thus causing an acute response to heat stress. The responses of cattle to conditions at Columbia, Mo. showed some acclimation to heat prior to the peak stress days, and therefore a dampened response was seen. It appears the extreme conditions at Columbia, Mo., 1999 were made severe by environmental conditions not simulated during this study (low wind speed and intensive solar radiation). Overall, it was determined while a cyclic heat stress treatment is a representative model to test heat stress in cattle, further heat stress experiments should be conducted in an actual feedlot.

  7. Future heat waves due to climate change threaten the survival of Posidonia oceanica seedlings.

    Science.gov (United States)

    Guerrero-Meseguer, Laura; Marín, Arnaldo; Sanz-Lázaro, Carlos

    2017-11-01

    Extreme weather events are major drivers of ecological change, and their occurrence is likely to increase due to climate change. The transient increases in atmospheric temperatures are leading to a greater occurrence of heat waves, extreme events that can produce a substantial warming of water, especially in enclosed basins such as the Mediterranean Sea. Here, we tested the effects of current and predicted heat waves on the early stages of development of the seagrass Posidonia oceanica. Temperatures above 27 °C limited the growth of the plant by inhibiting its photosynthetic system. It suffered a reduction in leaf growth and faster leaf senescence, and in some cases mortality. This study demonstrates that the greater frequency of heat waves, along with anticipated temperature rises in coming decades, are expected to negatively affect the germination of P. oceanica seedlings. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Long-term variability of heat waves in Argentina and recurrence probability of the severe 2008 heat wave in Buenos Aires

    Czech Academy of Sciences Publication Activity Database

    Rusticucci, M.; Kyselý, Jan; Almeira, G.; Lhotka, Ondřej

    2016-01-01

    Roč. 124, č. 3 (2016), s. 679-689 ISSN 0177-798X R&D Projects: GA MŠk 7AMB15AR001 Institutional support: RVO:68378289 Keywords : heat waves * long-term variability * climate extremes Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.640, year: 2016 http://link.springer.com/article/10.1007%2Fs00704-015-1445-7

  9. The possible role of MHD waves in heating the solar corona

    Science.gov (United States)

    Porter, Lisa J.; Klimchuk, James A.; Sturrock, Peter A.

    1994-01-01

    The possible role of waves in the heating of the solar corona has been investigated. A general dispersion relation has been derived for waves propagating in a homogeneous plasma subject to dissipation by viscosity and thermal conduction. The dissipation mechanisms have been incorporated self-consistently into the equations, and no assumptions about the strength of the damping have been made. Solutions of the sixth-order dispersion relation provide information on how the damping of both slow and fast mode waves depends upon the plasma density, temperature, field strength, and angle of propagation relative to the background magnetic field. We provide a detailed comparison to the standard approach, which is to solve for the wave quantities in the absence of dissipation and then to use these quantities in expressions for the heating due to viscosity and thermal conduction.

  10. Analysis and design of efficient planar leaky-wave antennas

    NARCIS (Netherlands)

    Ettore, M.

    2008-01-01

    This thesis deals with the effective design of planar leaky-wave antennas. The work describes a methodology based on the polar expansion of Green's function representations to address very different geometrical configurations which might appear to have little in common. In fact leaky waves with

  11. Efficient computations of wave loads on offshore structures

    DEFF Research Database (Denmark)

    Paulsen, Bo Terp

    The present thesis considers numerical computations of fully nonlinear wave impacts on bottom mounted surface piercing circular cylinders at intermediate water depths. The aim of the thesis is to provide new knowledge regarding wave loads on foundations for offshore wind turbines. Hence, the dime......The present thesis considers numerical computations of fully nonlinear wave impacts on bottom mounted surface piercing circular cylinders at intermediate water depths. The aim of the thesis is to provide new knowledge regarding wave loads on foundations for offshore wind turbines. Hence...... is carefully validated against experimental measurements of regular-, irregular- and multi-directional irregular waves. The ability of the numerical model to accurately reproduce experiments is also investigated. Wave impacts on a bottom mounted circular cylinder from steep regular waves are presented. Here......, the inline forces and the motion of the free surface is described as a function of the non-dimensional wave steepness, the relative water depth, the relative cylinder diameter and a co-existing current. From the computations, higher harmonic forces are determined and compared against the Morison equation...

  12. Burning Efficiency of Liquid Fuel in Heating System with Condensing Boilers

    Directory of Open Access Journals (Sweden)

    Olga Bancea

    2010-01-01

    Full Text Available The paper presents the results of a study concerning the efficiency of a heating installation with a condensing boiler using liquid fuel, equipped with an accumulator and burnt gases separator. The given up heat in the gas separator is taken over and accumulated through a heat pump. The energetic efficiency of the primary heating functioning regime was established at 94% after the measurements and at 95.8% through calculus.

  13. Propagation of waves in a gravitating and rotating anisotropic heat ...

    African Journals Online (AJOL)

    An inviscid, unbounded, collisionless, gravitating, rotating and heat conducting anisotropic plasma medium which is drifting is considered. The medium is assumed to be embedded in a strong magnetic field. A general dispersion relation is derived using normal mode analysis and its various limiting cases are discussed, ...

  14. The impact of heat waves and cold spells on respiratory emergency department visits in Beijing, China.

    Science.gov (United States)

    Song, Xuping; Wang, Shigong; Li, Tanshi; Tian, Jinhui; Ding, Guowu; Wang, Jiaxin; Wang, Jiexin; Shang, Kezheng

    2018-02-15

    The objectives of this article were (i) to find the association between extreme temperatures and respiratory emergency department (ED) visits and (ii) to explore the added effects of heat waves and cold spells on respiratory ED visits in Beijing from 2009 to 2012. A quasi-Poisson generalised linear model combined with a distributed lag non-linear model was performed to quantify this association. The results indicated that (i) ambient temperature related to respiratory ED visits exhibited a U-shaped association. The minimum-morbidity temperature was 21.5°C. (ii) the peak relative risk (RR) of cold spells on respiratory ED visits was observed in relatively mild cold spells with a threshold below the 3rd percentile for 4days (RR=1.885, 95% CI: 1.300-2.734), and there was a reduction in risk during extremely chilly cold spells (RR=1.811, 95% CI: 1.229-2.667). However, the risk of heat waves increased with the thresholds, and the greatest risk was found for extremely hot heat waves (RR=1.932, 95% CI: 1.461-2.554). (iii) the added effect of heat waves was small, and we observed that the added heat wave effect only introduced additional risk in females (RR=1.166, 95% CI: 1.007-1.349). No added effect of cold spells was identified. In conclusion, the main effects of heat waves and cold spells on respiratory ED visits showed different change trends. In addition, the added effects of extreme temperatures on respiratory ED visits were small and negligible. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Increasing heat waves and warm spells in India, observed from a multiaspect framework

    Science.gov (United States)

    Panda, Dileep Kumar; AghaKouchak, Amir; Ambast, Sunil Kumar

    2017-04-01

    Recent heat waves have been a matter of serious concern for India because of potential impacts on agriculture, food security, and socioeconomic progress. This study examines the trends and variability in frequency, duration, and intensity of hot episodes during three time periods (1951-2013, 1981-2013 and 1998-2013) by defining heat waves based on the percentile of maximum, minimum, and mean temperatures. The study also explores heat waves and their relationships with hydroclimatic variables, such as rainfall, terrestrial water storage, Palmer drought severity index, and sea surface temperature. Results reveal that the number, frequency, and duration of daytime heat waves increased considerably during the post-1980 dry and hot phase over a large area. The densely populated and agriculturally dominated northern half of India stands out as a key region where the nighttime heat wave metrics reflected the most pronounced amplifications. Despite the recent warming hiatus in India and other parts of the world, we find that both daytime and nighttime extreme measures have undergone substantial changes during or in the year following a dry year since 2002, with the probability distribution functions manifesting a hotter-than-normal climate during 1998-2013. This study shows that a few months preceding the 2010 record-breaking heat wave in Russia, India experienced the largest hot episode in the country's history. Interestingly, both these mega events are comparable in terms of their evolution and amplification. These findings emphasize the importance of planning for strategies in the context of the rising cooccurrence of dry and hot events.

  16. Time-Dependent Simulations of Fast-Wave Heated High-Non-Inductive-Fraction H-Mode Plasmas in the National Spherical Torus Experiment Upgrade

    Science.gov (United States)

    Taylor, Gary; Bertelli, Nicola; Gerhardt, Stefan P.; Hosea, Joel C.; Mueller, Dennis; Perkins, Rory J.; Poli, Francesca M.; Wilson, James R.; Raman, Roger

    2017-10-01

    30 MHz fast-wave heating may be an effective tool for non-inductively ramping low-current plasmas to a level suitable for initiating up to 12 MW of neutral beam injection on the National Spherical Tokamak Experiment Upgrade (NSTX-U). Previously on NSTX 30 MHz fast wave heating was shown to efficiently and rapidly heat electrons; at the NSTX maximum axial toroidal magnetic field (BT(0)) of 0.55 T, 1.4 MW of 30 MHz heating increased the central electron temperature from 0.2 to 2 keV in 30 ms and generated an H-mode plasma with a non-inductive fraction (fNI) ˜ 0.7 at a plasma current (Ip) of 300 kA. NSTX-U will operate at BT(0) up to 1 T, with up to 4 MW of 30 MHz power (Prf). Predictive TRANSP free boundary transport simulations, using the TORIC full wave spectral code to calculate the fast-wave heating and current drive, have been run for NSTX-U Ip = 300 kA H-mode plasmas. Favorable scaling of fNI with 30 MHz heating power is predicted, with fNI ≥ 1 for Prf ≥ 2 MW.

  17. The effects of latent heat release on the waves with Ekman pumping

    Science.gov (United States)

    Tang, C. M.

    1984-01-01

    The problem of the effects of the latent heat release on the waves with both upper and lower boundary frictional effects is investigated. The influence of the vertical shear of the basic wind in these models will be investigated. These investigations will shed some light on the method of solution to the problem of including the effect of Ekman pumping on the moist baroclinic waves in the model of Tang and Fichtl.

  18. Exact solutions of time fractional heat-like and wave-like equations with variable coefficients

    Directory of Open Access Journals (Sweden)

    Zhang Sheng

    2016-01-01

    Full Text Available In this paper, a variable-coefficient time fractional heat-like and wave-like equation with initial and boundary conditions is solved by the use of variable separation method and the properties of Mittag-Leffler function. As a result, exact solutions are obtained, from which some known special solutions are recovered. It is shown that the variable separation method can also be used to solve some others time fractional heat-like and wave-like equation in science and engineering.

  19. Pre-supernova outbursts via wave heating in massive stars - I. Red supergiants

    Science.gov (United States)

    Fuller, Jim

    2017-09-01

    Early observations of supernovae (SNe) indicate that enhanced mass-loss and pre-SN outbursts may occur in progenitors of many types of SNe. We investigate the role of energy transport via waves driven by vigorous convection during late-stage nuclear burning of otherwise typical 15 M⊙ red supergiant SN progenitors. Using mesa stellar evolution models including 1D hydrodynamics, we find that waves carry ˜107 L⊙ of power from the core to the envelope during core neon/oxygen burning in the final years before core collapse. The waves damp via shocks and radiative diffusion at the base of the hydrogen envelope, which heats up fast enough to launch a pressure wave into the overlying envelope that steepens into a weak shock near the stellar surface, causing a mild stellar outburst and ejecting a small (≲1 M⊙) amount of mass at low speed (≲50 km s-1) roughly one year before the SN. The wave heating inflates the stellar envelope but does not completely unbind it, producing a non-hydrostatic pre-SN envelope density structure different from prior expectations. In our models, wave heating is unlikely to lead to luminous Type IIn SNe, but it may contribute to flash-ionized SNe and some of the diversity seen in II-P/II-L SNe.

  20. THE ESTIMATION OF EFFICIENCY OF THE LADLES HEATING PROCESS

    OpenAIRE

    Wnęk, Mariusz; Rozpondek, Maciej

    2016-01-01

    The paper presents a system of drying and heating the metallurgical ladles. The ladle heating parameters significantly affect the metallurgical processes. The heating process target of the ceramic ladle lining can reduce the steel temperature in the furnace. It resulted in reduction of energy consumption what is an economic benefit. Adopted drying and heating rate of the ladle depends on the ladle refractory lining - an alkaline or an aluminosilicate. The temperature field uniformity of ceram...

  1. Land surface and atmospheric conditions associated with heat waves in the South Central United States

    Science.gov (United States)

    Lee, Eungul; Bieda, Rahama; Shanmugasundaram, Jothiganesh; Richter, Heather

    2017-04-01

    Exposure to extreme heat was reconstructed based on regional land-atmosphere processes from 1979 to 2010 in the South Central U.S. The study region surrounds the Chickasaw Nation (CN), a predominantly Native American population with a highly prevalent burden of climate-sensitive chronic diseases. Land surface and atmospheric conditions for summer heat waves were analyzed during spring (March-April-May, MAM) and summer (June-July-August, JJA) based on the Climate and Ocean: Variability, Predictability, and Change maximum temperature definition for heat wave frequency (HWF). The spatial-temporal pattern of HWF was determined using empirical orthogonal function (EOF) analysis and the corresponding principle component time series of the first EOF of HWF. Statistically significant analyses of observed conditions indicated that sensible heat increased and latent heat fluxes decreased with high HWF in the South Central U.S. The largest positive correlations of sensible heat flux to HWF and the largest negative correlations of latent heat flux to HWF were specifically observed over the CN. This is a significantly different energy transfer regime due to less available soil moisture during the antecedent MAM and JJA. The higher sensible heat from dry soil could cause significant warming from the near surface (> 2.0°C) to the lower troposphere (> 1.5°C), and accumulated boundary layer heat could induce the significant patterns of higher geopotential height and enhance anticyclonic circulations (negative vorticity anomaly) at the midtroposphere. Results suggested a positive land-atmosphere feedback associated with heat waves and called attention to the need for region-specific climate adaptation planning.

  2. Comments on the dissipation of hydromagnetic surface waves. [applicable to solar coronal plasma heating

    Science.gov (United States)

    Lee, M. A.

    1980-01-01

    A recent paper by Wentzel, which claims to calculate a plasma heating rate due to dissipation of surface waves in an ideal magnetohydrodynamic (MHD) fluid, is found to be in error in interpretation. A well-established general theorem pertaining to the conservative ideal MHD fluid requires that the normal mode calculated by Wentzel be oscillatory in time. Within ideal MHD, dissipation and plasma heating are therefore impossible.

  3. A new approach to the theory of heat conduction with finite wave speeds

    Directory of Open Access Journals (Sweden)

    Vito Antonio Cimmelli

    1991-05-01

    Full Text Available Relations between the physical models describing the heat conduction in solids and a phenomenological model leading to quasi-linear hyperbolic equations and systems of conservation laws are presented. A new semi-empirical temperature scale is introduced in terms of which a modified Fourier law is formulated. The hyperbolicity of the heat conduction equation is discussed together with some wave propagation problems.

  4. Individual and Public-Program Adaptation: Coping with Heat Waves in Five Cities in Canada

    Directory of Open Access Journals (Sweden)

    Mustapha Alhassan

    2011-12-01

    Full Text Available Heat Alert and Response Systems (HARS are currently undergoing testing and implementation in Canada. These programs seek to reduce the adverse health effects of heat waves on human health by issuing weather forecasts and warnings, informing individuals about possible protections from excessive heat, and providing such protections to vulnerable subpopulations and individuals at risk. For these programs to be designed effectively, it is important to know how individuals perceive the heat, what their experience with heat-related illness is, how they protect themselves from excessive heat, and how they acquire information about such protections. In September 2010, we conducted a survey of households in 5 cities in Canada to study these issues. At the time of the survey, these cities had not implemented heat outreach and response systems. The study results indicate that individuals’ recollections of recent heat wave events were generally accurate. About 21% of the sample reported feeling unwell during the most recent heat spell, but these illnesses were generally minor. Only in 25 cases out of 243, these illnesses were confirmed or diagnosed by a health care professional. The rate at which our respondents reported heat-related illnesses was higher among those with cardiovascular and respiratory illnesses, was higher among younger respondents and bore no relationship with the availability of air conditioning at home. Most of the respondents indicated that they would not dismiss themselves as “not at risk” and that they would cope with excessive heat by staying in air conditioned environments and keeping well hydrated. Despite the absence of heat outreach and education programs in their city, our respondents at least a rough idea of how to take care of themselves. The presence of air conditioning and knowledge of cooling centers is location-specific, which provides opportunities for targeting HARS interventions.

  5. Generalized power versus efficiency characteristics of heat engines: The thermoelectric generator as an instructive illustration

    Science.gov (United States)

    Gordon, J. M.

    1991-06-01

    The performance of real heat engines can be characterized by their power versus efficiency curves. Real heat engines with sources of irreversibility that include friction and heat leaks exhibit fundamentally different power versus efficiency curves than those predicted by many previous studies in the finite-time thermodynamics of endoreversible heat engines, in which finite-rate heat transfer was the only irreversibility considered. It is shown that the thermoelectric generator provides an instructive illustration of a cyclic, irreversible heat engine with a power versus efficiency curve that qualitatively reproduces the key features of the corresponding curves for real heat engines. The generic sources of irreversibility are easily identifiable and analytically expressed so as to reveal more transparently the basis for the power versus efficiency characteristic.

  6. On mechanism of non-heating sterilization using the underwater shock wave loading and gas formation

    Directory of Open Access Journals (Sweden)

    Ayumi Takemoto

    2007-12-01

    Full Text Available In the field where the thermal sterilization can’t be applied, the establishment of the sterilization technology with non-heating is strongly requested. The sterilization by pressurizing is one of the sterilization technology. Especially, the underwater shock wave causes scarcely heat in pressurizing because the pressurizing time is extremely short. That is, it is thought that the underwater shock wave enables non-heating sterilization that originates only in pressure. Hence, in this research, the underwater shock wave loading caused by explosive was used for non-heating sterilization. Saccharomyces cerevisiae, one of the budding yeast was used for experiments. S. cerevisiae starts fermentation by feeding the glucose, and causes CO2 within its body. There is the great density difference between cells of S. cerevisiae and the gas, hence, the acoustic impedance is different on the underwater shock wave transmission. Therefore, a strong reflected wave is caused on the boundary of the cell and the gas, and a remarkable expansion is caused. Fermented S. cerevisiae are sterilized by this phenomenon, and showed high sterilization rates. The sterilization rate by the underwater shock wave was low for not giving the glucose, that is, S. cerevisiae that had not fermented. The sterilization rate that had been done on three conditions was as follows in the order of higher. 1 Fermenting S. cerevisiae, high pressure. 2 Fermenting S. cerevisiae, low pressure. 3 Non-fermenting S. cerevisiae, high pressure. The detonation fuse was used in this experiment. There was an interesting phenomenon, that is, the sterilization rate was high at the side of detonation beginning, and it was decreased toward the direction. It is thought that this is related to a constant angle of the shock wave caused from the detonation fuse. A corresponding result to the phenomenon was gotten by the numerical analysis between the progress of the detonation and the change of pressure.

  7. Projection of temperature and heat waves for Africa with an ensemble of CORDEX Regional Climate Models

    Science.gov (United States)

    Dosio, Alessandro

    2017-07-01

    The most severe effects of global warning will be related to the frequency and severity of extreme events. We provide an analysis of projections of temperature and related extreme events for Africa based on a large ensemble of Regional Climate Models from the COordinated Regional climate Downscaling EXperiment (CORDEX). Results are presented not only by means of widely used indices but also with a recently developed Heat Wave Magnitude Index-daily (HWMId), which takes into account both heat wave duration and intensity. Results show that under RCP8.5, warming of more than 3.5 °C is projected in JFM over most of the continent, whereas in JAS temperatures over large part of Northern Africa, the Sahara and the Arabian peninsula are projected to increase up to 6 °C. Large increase in in the number of warm days (Tx90p) is found over sub equatorial Africa, with values up to more than 90 % in JAS, and more than 80 % in JFM over e.g., the gulf of Guinea, Central African Republic, South Sudan and Ethiopia. Changes in Tn90p (warm nights) are usually larger, with some models projecting Tn90p reaching 95 % starting from around 2060 even under RCP4.5 over the Gulf of Guinea and the Sahel. Results also show that the total length of heat spells projected to occur normally (i.e. once every 2 years) under RCP8.5 may be longer than those occurring once every 30 years under the lower emission scenario. By employing the recently developed HWMId index, it is possible to investigate the relationship between heat wave length ad intensity; in particular it is shown that very intense heat waves such as that occurring over the Horn of Africa may have values of HWMId larger than that of longer, but relatively weak, heat waves over West Africa.

  8. Power Efficiency of Systems Applied for Heating Building and Structure External Walls with Ventilated Air Spaces

    OpenAIRE

    I. F. Fialko; A. S. Statsenko

    2009-01-01

    The paper considers power-efficient systems applied for heating building and structure external walls with ventilated air spaces and prescribes directions and problems pertaining to power-efficiency improvement of such systems.

  9. Detecting Crop Functional Response to a Heat Wave using Airborne Reflectance and Sun-induced Chlorophyll Fluorescence Measurements

    Science.gov (United States)

    Yang, P.; Van der Tol, C.; Rascher, U.; Damm, A.; Schickling, A.; Verhoef, W.

    2016-12-01

    This study presents an analysis of airborne measured reflectance (R) and solar-induced chlorophyll fluorescence (SIF) as indicators of high temperature stress in agricultural crops. We used atmospherically corrected R and retrievals of SIF in the O2-A band as obtained from HyPlant data over C3 crops (rapeseed, wheat and barley) and a C4 crop (corn) in Germany before (30th June) and during (2nd July) a heat wave in 2015. The availability of airborne data during this heat wave allowed us to detect fluorescence emission efficiency changes as an indicator of crop photosynthetic performance in response to temperature fluctuations. We found that SIF is affected relatively stronger by heat stress than R. This is according to expectation, because the R spectrum is determined by leaf properties and canopy structure, whereas top-of-canopy (TOC) SIF is also affected by the temperature dependent efficiencies of photochemical and non-photochemical quenching of fluorescence. With the model 'Soil Canopy Observation of Photosynthesis and Energy fluxes (SCOPE), we differentiated leaf optical parameters and canopy structure from the fluorescence quantum emission efficiency (FQE), i.e. the ratio of fluorescence production to light absorption of photosystems. The leaf optical and canopy structure parameters were retrieved from R by inversion of the radiative transfer module 'RTMo' of SCOPE. The retrieved parameters were further used to estimate the FQE from SIF measurements. It appeared that both the leaf water content CW and the FQE responded to the heat wave, but the responses were different for C3 and C4 crops. A slight reduction of CW occurred in C3 crops between the two days, but not in the C4 crop. The reduction of FQE was only significant in C3 crops, and ranged from 18% to 31% for various C3 species. These findings agree with the general knowledge that C4 plants are better adapted to high temperature than C3 plants, and comply with simulations from a biochemical model for C3

  10. On the strongly damped wave equation and the heat equation with mixed boundary conditions

    Directory of Open Access Journals (Sweden)

    Aloisio F. Neves

    2000-01-01

    Full Text Available We study two one-dimensional equations: the strongly damped wave equation and the heat equation, both with mixed boundary conditions. We prove the existence of global strong solutions and the existence of compact global attractors for these equations in two different spaces.

  11. Future changes in heat-waves, droughts and floods in 571 European cities

    Science.gov (United States)

    Guerreiro, Selma; Dawson, Richard; Kilsby, Chris; Lewis, Elizabeth; Ford, Alistair

    2017-04-01

    Future changes in heat-waves, droughts and floods were assessed for 571 European cities. We used all available climate model runs from the Coupled Model Intercomparison Project Phase 5 - CMIP5 - for their higher emission scenario (RCP8.5) and grouped the projections into Low, Mid and High impact scenarios. This resulted in impact projections outside the range of published literature, but enabled us to better understand uncertainties in future climate projections (both due to climate model errors but also the effects of natural variability) therefore providing the basis for broad scale risk analysis and thereafter identification of robust adaptation strategies. While heat-waves will worsen for every European city, changes in droughts and floods are spatially variable and climate model dependent. The largest increases in the number of heat-wave days are shown to be in southern Europe, but higher heat-wave maximum temperature increases are expected in the mid-latitudes. In the low impact scenario, drought conditions are expected to intensify only in southern Europe while river flooding in expected to worsen in the north. However, in the high impact scenario most European cities show increases in both drought conditions and river flooding. There is a very wide range of projections for future changes in Europe with disagreement between different studies, partly due to their methodological differences but potentially also due to the small number of climate model runs that limits the uncertainties due to natural variability and model errors that each study captures.

  12. The Bermuda Triangle mysteries: an explanation based on the diffraction of heat waves

    Energy Technology Data Exchange (ETDEWEB)

    Njau, E.C. [Dar es Salaam Univ. (Tanzania, United Republic of). Dept. of Physics

    1995-12-31

    Studies based on actual meteorological records [E.C. Njau, Nuovo Cimento 15C, 17-23 (1992)] as well as analytical methods [E.C. Njau, Proc. Ind. Natn. Sci. Acad., 61A (4) (1995); Renewable Energy 4, 261-263 (1994)] have established the continuous existence of a series of large-scale, Eastward-moving heat waves along the Earth`s surface, whose individual crests and troughs are stretched approximately along the geographical North-South direction. In moving across the American continent, these waves encounter a line of physical barriers formed by the lofty Rocky and Andes ranges of mountains, which is continuous except for a significant gap or opening between Colombia and Mexico. This line of physical barriers consistently maintains a maximum height of 3000-4000 m between latitudes 40{sup o}S and 55{sup o}N except for a significant opening or slit located between Mexico and Colombia where the maximum height hardly exceeds 600 m. The Eastward-moving heat waves are thus incident obliquely on an approximately single-slit barrier when crossing the American continent and those parts of the waves which filter through this single slit essentially form some kind of single-slit diffraction (heat) patterns in, around and past the Bermuda Triangle. These diffraction heat patterns give rise to corresponding weather and ocean patterns which, to a large extent, account for the mysteries already noted in the Bermuda region. (Author)

  13. Observed changes in seasonal heat waves and warm temperature extremes in the Romanian Carpathians

    Science.gov (United States)

    Micu, Dana; Birsan, Marius-Victor; Dumitrescu, Alexandru; Cheval, Sorin

    2015-04-01

    Extreme high temperature have a large impact on environment and human activities, especially in high elevation areas particularly sensitive to the recent climate warming. The climate of the Romanian Carpathians became warmer particularly in winter, spring and summer, exibiting a significant increasing frequency of warm extremes. The paper investigates the seasonal changes in the frequency, duration and intensity of heat waves in relation to the shifts in the daily distribution of maximum temperatures over a 50-year period of meteorological observations (1961-2010). The paper uses the heat wave definition recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI) and exploits the gridded daily dataset of maximum temperature at 0.1° resolution (~10 km) developed in the framework of the CarpatClim project (www.carpatclim.eu). The seasonal changes in heat waves behavior were identified using the Mann-Kendall non-parametric trend test. The results suggest an increase in heat wave frequency and a lengthening of intervals affected by warm temperature extremes all over the study region, which are explained by the shifts in the upper (extreme) tail of the daily maximum temperature distribution in most seasons. The trends are consistent across the region and are well correlated to the positive phases of the East Atlantic Oscillation. Our results are in good agreement with the previous temperature-related studies concerning the Carpathian region. This study was realized within the framework of the project GENCLIM, financed by UEFISCDI, code PN-II 151/2014.

  14. GRACE-derived terrestrial water storage depletion associated with the 2003 European heat wave

    DEFF Research Database (Denmark)

    Andersen, Ole Baltazar; Seneviratne, S.I.; Hinderer, J.

    2005-01-01

    water storage depletion observed from GRACE can be related to the record-breaking heat wave that occurred in central Europe in 2003. We validate the measurements from GRACE using two independent hydrological estimates and direct gravity observations from superconducting gravimeters in Europe. All...

  15. Combined effects of heat waves and droughts on avian communities across the conterminous United States

    Science.gov (United States)

    Thomas P. Albright; Anna M. Pidgeon; Chadwick D. Rittenhouse; Murray K. Clayton; Brian D. Wardlow; Curtis H. Flather; Patrick D. Culbert; Volker C. Radeloff

    2010-01-01

    Increasing surface temperatures and climatic variability associated with global climate change are expected to produce more frequent and intense heat waves and droughts in many parts of the world. Our goal was to elucidate the fundamental, but poorly understood, effects of these extreme weather events on avian communities across the conterminous United States....

  16. Climate change and heat and cold wave frequencies for different locations in Europe

    Science.gov (United States)

    Parey, Sylvie; Thu Huong Hoang, Thi; Dacunha-Castelle, Didier

    2014-05-01

    Heat and cold waves are important meteorological events related to electricity production and consumption. Therefore, we developed a stochastic model for temperature able to correctly reproduce extreme events and this tool can be used to downscale climate model simulations. As a matter of fact, the stochastic model simulates the residues after removing trends and seasonalities in the mean and the variance of temperature time-series. Thus, once the model has been calibrated on an observed time-series, future time series can be re-constructed from the modelled residues and the trends and seasonalities given by any climate model simulation, suitably corrected. This technique allows increasing the number of temperature time-series in order to infer the significance of possible changes. When applied to study the frequency changes of heat or cold waves of different lengths, from 1 day to more than 15 days, preliminary results have shown that the changes are significant only for very long heat or cold waves in the near future. This first analysis will be extended to further locations in Europe and future time periods, using the CMIP5 simulation results of different climate models, in order to check the robustness of such results and to further investigate possible changes in the frequencies of heat and cold waves. The presentation will thus describe the used methodology and detail the main results obtained when applied for different temperature time-series.

  17. A remotely steered millimetre wave launcher for electron cyclotron heating and current drive on ITER

    NARCIS (Netherlands)

    Bongers, W. A.; M. F. Graswinckel,; Goede, A. P. H.; Kasparek, W.; Danilov, I.; Curto, A. F.; M.R. de Baar,; van den Berg, M. A.; Donne, A. J. H.; Elzendoorn, B. S. Q.; Heidinger, R.; Ivanov, P.; Kruijt, O. G.; Lamers, B.; Meier, A.; Piosczyk, B.; Plaum, B.; Ronden, D. M. S.; Thoen, D. J.; Schmid, M.; Verhoeven, A. G. A.

    2010-01-01

    High-power millimetre wave beams employed on ITER for heating and Current drive at the 170 GHz electron cyclotron resonance frequency require agile steering and tight focusing of the beams to suppress neoclassical tearing modes. This paper presents experimental validation of the remote steering (RS)

  18. The 2010 Pakistan Flood and Russian Heat Wave: Teleconnection of Hydrometeorological Extremes

    Science.gov (United States)

    Lau, William K. M.; Kim, Kyu-Myong

    2012-01-01

    In this paper, preliminary results are presented showing that the two record-setting extreme events during 2010 summer (i.e., the Russian heat wave-wildfires and Pakistan flood) were physically connected. It is found that the Russian heat wave was associated with the development of an extraordinarily strong and prolonged extratropical atmospheric blocking event in association with the excitation of a large-scale atmospheric Rossby wave train spanning western Russia, Kazakhstan, and the northwestern China-Tibetan Plateau region. The southward penetration of upper-level vorticity perturbations in the leading trough of the Rossby wave was instrumental in triggering anomalously heavy rain events over northern Pakistan and vicinity in mid- to late July. Also shown are evidences that the Russian heat wave was amplified by a positive feedback through changes in surface energy fluxes between the atmospheric blocking pattern and an underlying extensive land region with below-normal soil moisture. The Pakistan heavy rain events were amplified and sustained by strong anomalous southeasterly flow along the Himalayan foothills and abundant moisture transport from the Bay of Bengal in connection with the northward propagation of the monsoonal intraseasonal oscillation.

  19. Analysis of heat wave occurrences in the Carpathian basin using regional climate model simulations

    Science.gov (United States)

    Bartha, E. B.; Pongracz, R.; Bartholy, J.

    2012-04-01

    Human health is very likely affected by regional consequences of global warming. One of the most severe impacts is probably associated to temperature-related climatological extremes, such as heat waves. In the coming decades hot conditions in most regions of the world are very likely to occur more frequently and more intensely than in the recent decades. In order to develop adaptation and mitigation strategies on local scale, it is essential to analyze the projected changes related to warming climatic conditions including heat waves. In 2004, a Heat Health Watch Warning System was developed in Hungary on the basis of a retrospective analysis of mortality and meteorological data to anticipate heat waves that may result in a large excess of mortality. In the frame of this recently introduced Health Watch System, three levels of heat wave warning are applied. They are associated to the daily mean temperature values, and defined as follows: - Warning level 1 (advisory for internal use) is issued when the daily mean temperature exceeds 25 °C. - Warning level 2 (heat wave watch) is issued when the daily mean temperature for at least 3 consecutive days exceeds 25 °C. - Warning level 3 (heat wave alert) is issued when the daily mean temperature for at least 3 consecutive days exceeds 27 °C. In the present study, frequency of the above climatic conditions are analyzed using regional climate model (RCM) experiments are analyzed for the recent past and the coming decades (1961-2100) for the Carpathian basin. At the Dept. of Meteorology, Eotvos Lorand University two different RCMs have been adapted: RegCM (with 10 km horizontal resolution, originally developed by Giorgi et al., currently, available from the International Centre for Theoretical Physics, ICTP) and PRECIS (with 25 km horizontal resolution, developed at the UK Met Office, Hadley Centre). Their initial and lateral boundary conditions have been provided by global climate models ECHAM and HadCM3, respectively. For

  20. Geothermal heat. Potential, danger, efficiency; Erdwaerme. Potential, Gefahr, Nutzen

    Energy Technology Data Exchange (ETDEWEB)

    Reichel, Wolfgang [Ingenieurbuero Timmer Reichel GmbH, Haan (Germany)

    2010-07-01

    The author of the contribution under consideration reports on the potential, danger and utilization of geothermal heat. Geothermal heat promises the solution of numerous energy problems. From the use of near-surface layers which substantially are affected by enviromental impacts such as solar radiation up to the depth use of the heat flow from the interior of the earth, there exist very different energy sources which are to be considered separately for each application.

  1. Commercial high efficiency dehumidification systems using heat pipes

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-01

    An improved heat pipe design using separately connected two-section one-way flow heat pipes with internal microgrooves instead of wicks is described. This design is now commercially available for use to increase the dehumidification capacity of air conditioning systems. The design also includes a method of introducing fresh air into buildings while recovering heat and controlling the humidity of the incoming air. Included are applications and case studies, load calculations and technical data, and installation, operation, and maintenance information.

  2. The Impact of Heat Waves on Occurrence and Severity of Construction Accidents.

    Science.gov (United States)

    Rameezdeen, Rameez; Elmualim, Abbas

    2017-01-11

    The impact of heat stress on human health has been extensively studied. Similarly, researchers have investigated the impact of heat stress on workers' health and safety. However, very little work has been done on the impact of heat stress on occupational accidents and their severity, particularly in South Australian construction. Construction workers are at high risk of injury due to heat stress as they often work outdoors, undertake hard manual work, and are often project based and sub-contracted. Little is known on how heat waves could impact on construction accidents and their severity. In order to provide more evidence for the currently limited number of empirical investigations on the impact of heat stress on accidents, this study analysed 29,438 compensation claims reported during 2002-2013 within the construction industry of South Australia. Claims reported during 29 heat waves in Adelaide were compared with control periods to elicit differences in the number of accidents reported and their severity. The results revealed that worker characteristics, type of work, work environment, and agency of accident mainly govern the severity. It is recommended that the implementation of adequate preventative measures in small-sized companies and civil engineering sites, targeting mainly old age workers could be a priority for Work, Health and Safety (WHS) policies.

  3. Neonates in Ahmedabad, India, during the 2010 heat wave: a climate change adaptation study.

    Science.gov (United States)

    Kakkad, Khyati; Barzaga, Michelle L; Wallenstein, Sylvan; Azhar, Gulrez Shah; Sheffield, Perry E

    2014-01-01

    Health effects from climate change are an international concern with urban areas at particular risk due to urban heat island effects. The burden of disease on vulnerable populations in non-climate-controlled settings has not been well studied. This study compared neonatal morbidity in a non-air-conditioned hospital during the 2010 heat wave in Ahmedabad to morbidity in the prior and subsequent years. The outcome of interest was neonatal intensive care unit (NICU) admissions for heat. During the months of April, May, and June of 2010, 24 NICU admissions were for heat versus 8 and 4 in 2009 and 2011, respectively. Both the effect of moving the maternity ward and the effect of high temperatures were statistically significant, controlling for each other. Above 42 degrees Celsius, each daily maximum temperature increase of a degree was associated with 43% increase in heat-related admissions (95% CI 9.2-88%). Lower floor location of the maternity ward within hospital which occurred after the 2010 heat wave showed a protective effect. These findings demonstrate the importance of simple surveillance measures in motivating a hospital policy change for climate change adaptation-here relocating one ward-and the potential increasing health burden of heat in non-climate-controlled institutions on vulnerable populations.

  4. Heat transfer measurements in swept shock wave/turbulent boundary-layer interactions

    Science.gov (United States)

    Lee, Yeol

    An experimental research program providing basic knowledge and establishing a database on the heat transfer in three-dimensional shock wave/boundary-layer interaction is described. High thermal loading in such interactions constitutes a fundamental problem of critical concern to future supersonic and hypersonic flight vehicles. A turbulent boundary-layer on a flat plate is subjected to interactions with swept planar shock waves generated by a sharp fin. Fin angles from 10 deg to 20 deg at freestream Mach numbers 3.0 and 4.0 produce a variety of interaction strengths from weak to very strong. A foil heater generates a uniform heat flux over the surface of interest and thin-film resistance thermometers mounted on it are used to measure the local surface temperature. The heat convection equation is then used to calculate the local heat transfer coefficients. The present heat transfer technique is applied to measure heat transfer distributions for 5 different interaction cases. The experimental data are compared with numerical Navier-Stokes solutions. The estimation of total uncertainty of the present measurements is about plus or minus 10 percent, which makes them suitable for CFD code validation purposes. The measured peak heat transfer data are correlated with the normal Mach number based on the concept of the quasi-conical nature of such interactions, and the results show good agreement with other experimental data.

  5. The Impact of Heat Waves on Occurrence and Severity of Construction Accidents

    Directory of Open Access Journals (Sweden)

    Rameez Rameezdeen

    2017-01-01

    Full Text Available The impact of heat stress on human health has been extensively studied. Similarly, researchers have investigated the impact of heat stress on workers’ health and safety. However, very little work has been done on the impact of heat stress on occupational accidents and their severity, particularly in South Australian construction. Construction workers are at high risk of injury due to heat stress as they often work outdoors, undertake hard manual work, and are often project based and sub-contracted. Little is known on how heat waves could impact on construction accidents and their severity. In order to provide more evidence for the currently limited number of empirical investigations on the impact of heat stress on accidents, this study analysed 29,438 compensation claims reported during 2002–2013 within the construction industry of South Australia. Claims reported during 29 heat waves in Adelaide were compared with control periods to elicit differences in the number of accidents reported and their severity. The results revealed that worker characteristics, type of work, work environment, and agency of accident mainly govern the severity. It is recommended that the implementation of adequate preventative measures in small-sized companies and civil engineering sites, targeting mainly old age workers could be a priority for Work, Health and Safety (WHS policies.

  6. Heat wave over India during summer 2015: an assessment of real time extended range forecast

    Science.gov (United States)

    Pattanaik, D. R.; Mohapatra, M.; Srivastava, A. K.; Kumar, Arun

    2017-08-01

    Hot winds are the marked feature of summer season in India during late spring preceding the climatological onset of the monsoon season in June. Some years the conditions becomes very vulnerable with the maximum temperature ( T max) exceeding 45 °C for many days over parts of north-western, eastern coastal states of India and Indo-Gangetic plain. During summer of 2015 (late May to early June) eastern coastal states, central and northwestern parts of India experienced severe heat wave conditions leading to loss of thousands of human life in extreme high temperature conditions. It is not only the loss of human life but also the animals and birds were very vulnerable to this extreme heat wave conditions. In this study, an attempt is made to assess the performance of real time extended range forecast (forecast up to 3 weeks) of this scorching T max based on the NCEP's Climate Forecast System (CFS) latest version coupled model (CFSv2). The heat wave condition was very severe during the week from 22 to 28 May with subsequent week from 29 May to 4 June also witnessed high T max over many parts of central India including eastern coastal states of India. The 8 ensemble members of operational CFSv2 model are used once in a week to prepare the weekly bias corrected deterministic (ensemble mean) T max forecast for 3 weeks valid from Friday to Thursday coinciding with the heat wave periods of 2015. Using the 8 ensemble members separately and the CFSv2 corresponding hindcast climatology the probability of above and below normal T max is also prepared for the same 3 weeks. The real time deterministic and probabilistic forecasts did indicate impending heat wave over many parts of India during late May and early June of 2015 associated with strong northwesterly wind over main land mass of India, delaying the sea breeze, leading to heat waves over eastern coastal regions of India. Thus, the capability of coupled model in providing early warning of such killer heat wave can be very

  7. EFFICIENCY OF THE USE OF HEAT PUMPS ON THE CHP PLANTS

    Directory of Open Access Journals (Sweden)

    Juravleov A.A.

    2007-04-01

    Full Text Available The work is dedicated to the calculus of the efficiency of the use of heat pumps on the CHP plants. There are presented the interdependences between the pay-back period and NPV of heat pump and the price of 1 kWt of thermal power of heat pump and of the tariff of electricity.

  8. Evaluation of Energy Efficiency Performance of Heated Windows

    Science.gov (United States)

    Jammulamadaka, Hari Swarup

    The study about the evaluation of the performance of the heated windows was funded by the WVU Research Office as a technical assistance award at the 2014 TransTech Energy Business Development Conference to the Green Heated Glass company/project owned by Frank Dlubak. The award supports a WVU researcher to conduct a project important for commercialization. This project was awarded to the WVU Industrial Assessment Center in 2015. The current study attempted to evaluate the performance of the heated windows by developing an experimental setup to test the window at various temperatures by varying the current input to the window. The heated double pane window was installed in an insulated box. A temperature gradient was developed across the window by cooling one side of the window using gel based ice packs. The other face of the window was heated by passing current at different wattages through the window. The temperature of the inside and outside panes, current and voltage input, room and box temperature were recorded, and used to calculate the apparent R-value of the window when not being heated vs when being heated. It has been concluded from the study that the heated double pane window is more effective in reducing heat losses by as much as 50% than a non-heated double pane window, if the window temperature is maintained close to the room temperature. If the temperature of the window is much higher than the room temperature, the losses through the window appear to increase beyond that of a non-heated counterpart. The issues encountered during the current round of experiments are noted, and recommendations provided for future studies.

  9. Large Eddy Simulation of Disturbance Waves and Heat Transfer in Annular Flows

    Science.gov (United States)

    Hewitt, Geoff; Yang, Junfeng; Matar, Omar

    2014-11-01

    A numerical method for forced convective boiling in an annulus needs to be developed in order to elucidate the reason for nucleation enhancement by disturbance waves. The benchmark test case is the experiment of Barbosa et al., in which nucleate boiling in a liquid film, droplet entrainment, disturbance waves of the liquid film, and their interaction were observed. We first develop a numerical strategy to model the development of disturbance waves in annular flows in which the highly turbulent gas core flow drives the laminar liquid flow upwards using advanced CFD tool TransAT. Then, the heat transfer process in the non-boiling annular flow was investigated to provide insight into the temperature gradient underneath the wave region. Agreement with experimental data for the temperature field could be improved by accounting for phase change in the models. However, the modelling results are still indicative and show that heat transfer is hindered in the wave region. The local overheat zones underneath the disturbance wave could play key roles activating the nucleation boiling sites. NURESAFE Project, and ASCOMP Co. (for use of TransAT code).

  10. Alfven wave trapping, network microflaring, and heating in solar coronal holes

    Science.gov (United States)

    Moore, R. L.; Suess, S. T.; Musielak, Z. E.; An, C.-H.

    1991-01-01

    Fresh evidence that much of the heating in coronal holes is provided by Alfven waves is presented. This evidence comes from examining the reflection of Alfven waves in an isothermal hydrostatic model coronal hole with an open magnetic field. Reflection occurs if the wavelength is as long as the order of the scale height of the Alfven velocity. For Alfven waves with periods of about 5 min, and for realistic density, magnetic field strength, and magnetic field spreading in the model, the waves are reflected back down within the model hole if the coronal temperature is only slightly less than 1.0 x 10 to the 6th K, but are not reflected and escape out the top of the model if the coronal temperature is only slightly greater than 1.0 x 10 to the 6th K. Because the spectrum of Alfven waves in real coronal holes is expected to peak around 5 min and the temperature is observed to be close to 1.0 x 10 to the 6th K, the sensitive temperature dependence of the trapping suggests that the temperature in coronal holes is regulated by heating by the trapped Alfven waves.

  11. A Bayesian Framework for Exploring Drought-Heat Wave Relationships via Vine Copula

    Science.gov (United States)

    Cheng, L.; Hoerling, M. P.

    2016-12-01

    This study proposes a framework for exploring contributions of underlying factors to extreme weather and climate events via vine copulas. In particular, this framework features a quantitative way for evaluating the importance of conditional relationships between variables and processes that capture underlying physical factors involved in their interdependence. Specifically, a variety of bivariate copulas is incorporated to construct a wide range of joint dependence structures for climate-related extreme events, e.g. building distributions for describing the statistics of heat waves. Underlying factors relevant for the extreme event are then taken into account via the conditioning sets of vine copulas. These quantify changes in the occurrence and severity of the extreme event owing to the co-action of various factors, e.g. conditioning the distribution of heat waves upon soil moisture deficits, precipitation deficits etc. A Bayesian inference approach is integrated into the multi-dimensional vine copulas, which facilitate parameter inference, uncertainty assessments, and the incorporation of various levels of conditioning sets in the vine copula. To illustrate, the proposed framework is applied to explore the relationship between droughts and heat waves over various regions of the contiguous United States that are distinguished by so-called energy-limited versus water-limited climatologies. We use data from large ensembles of CESM1 transient simulations and compare changes in the severity and likelihood of heat waves in response to soil moisture deficits relative to the climatology of the historical, current and future climate states, respectively. We explore whether the sensitivity of heat waves to soil moisture conditions is different for the climate regions mentioned above, and whether each region has unique attributes of sensitivity to human-induced climate change.

  12. Predictability and Spatial Characteristics of New-York-City-Area Heat Waves

    Science.gov (United States)

    Raymond, C.; Horton, R. M.

    2016-12-01

    The origins, characteristics, and predictability of extreme heat waves in the Northeast U.S. are simultaneously examined at multiple scales, using hourly observational data from 1948-2014 and focusing in particular on the region surrounding New York City. A novel definition of heat waves - incorporating both temperature and moisture at hourly resolution - is used to identify 3-to-5-day heat waves whose dynamics are then analyzed from 3 weeks prior to 3 weeks subsequent to the event. Inter-event differences in dynamics such as the strength and position of geopotential-height anomalies; the strength, persistence, and orientation of sea breezes; and the dominant 850-hPa wind azimuth, all of which are filtered via local terrain and land-use to create differences in conditions between events at specific locations. In particular, using composite maps and back trajectories, they are found to play an important role in creating mesoscale differences in low-level moisture content, from one side of the metropolitan area to the other. Evidence is presented supporting the influence of coastline orientation in explaining the differences in the relationships between wind azimuth and temperature & moisture advection between New York City proper and northern New Jersey. Self-organizing maps are employed to classify heat waves based on the small-scale differences in temperature and moisture between events, and the results of this classification are then used in correlations with synoptic- and hemispheric-scale geopotential-height anomalies. Considerable predictability of event type on the small-scale (as well as occurrence of a heat wave of any kind) is found, originating primarily from central Pacific and western Atlantic SSTs.

  13. Electron heating via mode converted ion Bernstein waves in the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Bonoli, P.T.; OShea, P.; Brambilla, M.; Golovato, S.N.; Hubbard, A.E.; Porkolab, M.; Takase, Y.; Boivin, R.L.; Bombarda, F.; Christensen, C.; Fiore, C.L.; Garnier, D.; Goetz, J.; Granetz, R.; Greenwald, M.; Horne, S.F.; Hutchinson, I.H.; Irby, J.; Jablonski, D.; LaBombard, B.; Lipschultz, B.; Marmar, E.; May, M.; Mazurenko, A.; McCracken, G.; Nachtrieb, R.; Niemczewski, A.; Ohkawa, H.; Pappas, D.A.; Reardon, J.; Rice, J.; Rost, C.; Schachter, J.; Snipes, J.A.; Stek, P.; Takase, K.; Terry, J.; Wang, Y.; Watterson, R.L.; Welch, B.; Wolfe, S.M. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    1997-05-01

    Highly localized direct electron heating [full width at half-maximum (FWHM){congruent}0.2a] via mode converted ion Bernstein waves has been observed in the Alcator C-Mod Tokamak [I. H. Hutchinson {ital et al.}, Phys. Plasmas {bold 1}, 1511 (1994)]. Electron heating at or near the plasma center (r/a{ge}0.3) has been observed in H({sup 3}He) discharges at B{sub 0}=(6.0{endash}6.5)T and n{sub e}(0){congruent}1.8{times}10{sup 20}m{sup {minus}3}. [Here, the minority ion species is indicated parenthetically.] Off-axis heating (r/a{ge}0.5) has also been observed in D({sup 3}He) plasmas at B{sub 0}=7.9T. The concentration of {sup 3}He in these experiments was in the range of n{sub 3{sub He}}/n{sub e}{congruent}(0.2{endash}0.3) and the locations of the mode conversion layer and electron heating peak could be controlled by changing the {sup 3}He concentration or toroidal magnetic field (B{sub 0}). The electron heating profiles were deduced using a rf modulation technique. Detailed comparisons with one-dimensional and toroidal full-wave models in the ion cyclotron range of frequencies have been carried out. One-dimensional full-wave code predictions were found to be in qualitative agreement with the experimental results. Toroidal full-wave calculations indicated the importance of volumetric and wave focusing effects in the interpretation of the experimental results. {copyright} {ital 1997 American Institute of Physics.}

  14. Nonresonant absorption of shear Alfven waves. [in solar coronal heating and solar wind acceleration

    Science.gov (United States)

    Strauss, H. R.

    1991-01-01

    Resonant absorption of shear Alfven waves is thought to be a likely candidate to explain heating of the solar corona and acceleration of the solar wind. A difficulty with the theory is that the absorption process is slow. Moreover, heating occurs in a very thin layer. A faster absorption mechanism is nonresonant absorption by compressional viscosity, in a curved magnetic field. Heating is nonresonant and is not localized to a narrow layer. The effect could be quite important where the solar coronal magnetic field is strongly curved, in the chromosphere. It could also be important on open field lines in the upper corona, where the compressional viscosity is large. It might imply that a significant part of outgoing Alfven waves are absorbed in the corona.

  15. Economic and environmental efficiency of district heating plants

    DEFF Research Database (Denmark)

    Agrell, Per J.; Bogetoft, Peter

    2005-01-01

    heat, have arbitrary valuation.This study concerns the most developed European district heating and cogeneration system, the Danish.By assessing environmental and economic ef¿ciency, the impact of governmental, market and managerial imperfections are estimated.The principal methodological base...

  16. Exergetic efficiency optimization for an irreversible heat pump ...

    Indian Academy of Sciences (India)

    This paper deals with the performance analysis and optimization for irreversible heat pumps working on reversed Brayton cycle with constant-temperature heat reservoirs ... Institute of Civil & Architectural Engineering, Beijing University of Technology, Beijing 100124, People's Republic of China; Postgraduate School, Naval ...

  17. Efficiency of wave impeding barrier in pipeline construction under ...

    Indian Academy of Sciences (India)

    They should be protected from earthquake disaster especially when they pass through high seismicity zones. The installation of wave impeding barriers (WIB) below the vulnerable infrastructures as pipelines established in soft soil can be used to reduce the effect of the earthquake induced ground borne vibrations. In this ...

  18. An efficient algorithm for computation of solitary wave solutions to ...

    Indian Academy of Sciences (India)

    2017-09-08

    Sep 8, 2017 ... ... reliable mathematical technique. By using the proposed technique, we attain soliton wave solution of various types. It is observed that the technique under discussion is user friendly with minimum computational work, and can be extended for physical problems of different nature in mathematical physics.

  19. Account of heat convection by Rayleigh streaming in the description of wave amplitude growth and stabilization in a standing wave thermoacoustic prime-mover.

    Science.gov (United States)

    Penelet, Guillaume; Guedra, Matthieu; Gusev, Vitalyi

    2012-09-01

    This study focuses on the transient regime of wave amplitude growth and stabilization occuring into a standing wave thermoacoustic engine. Experiments are performed on a standing wave thermoacoustic oscillator. They show that the transient regime leading to steady state sound exhibits complicated dynamics, like the systematic overshoot of wave amplitude before its final stabilization, and the spontaneous and periodic switch on/off of the thermoacoustic instability at constant heat power supply. A simplified model is presented which describes wave amplitude growth from the coupled equations governing thermoacoustic amplification and unsteady heat transfer. In this model, the assumption of a one-dimensional temperature profile is retained and the equations describing heat transfer through the thermoacoustic core are coupled to that describing wave amplitude growth. These equations include the simplified description of two processes saturating wave amplitude growth, i.e. thermoacoustic heat pumping by acoustic waves and heat convection by Rayleigh streaming. It is notably shown that both effects could be responsible of the observed overshoot process.

  20. ONE OF THE WAYS TO RISE THE EFFICIENCY OF THE KISHINEV TOWN HEAT AND POWER STATIONS

    Directory of Open Access Journals (Sweden)

    Maximuk E.P.

    2010-04-01

    Full Text Available Methods to rise the efficiency of fuel using at town heat and power stations are discussed in detail. It is shown that application of hot water/exhaust absorption chillers allow to use heat energy surplus especially in warm season. As the results, the consumption of heat energy from the power stations is more constant during the year, the efficiency of fuel using is higher, and economics is better. Different technological schemes are discussed in detail.

  1. The possible role of high-frequency waves in heating solar coronal loops

    Science.gov (United States)

    Porter, Lisa J.; Klimchuk, James A.; Sturrock, Peter A.

    1994-01-01

    We investigate the role of high-frequency waves in the heating of solar active region coronal loops. We assume a uniform background magnetic field, and we introduce a density stratification in a direction perpendicular to this field. We focus on ion compressive viscosity as the damping mechanism of the waves. We incorporate viscosity self-consistently into the equations, and we derive a dispersion relation by adopting a slab model, where the density inside the slab is greater than that outside. Such a configuration supports two types of modes: surface waves and trapped body waves. In order to determine under what conditions these waves may contribute to the heating of active regions, we solve our dispersion relation for a range of densities, temperatures, magnetic field strengths, density ratios, wavevector magnitudes, wavevector ratios, and slab widths. We find that surface waves exhibit very small damping, but body waves can potentially damp at rates needed to balance radiative losses. However, the required frequencies of these body waves are very high. For example, the wave frequency must be at least 5.0/s for a slab density of 10(exp 9,5)/cc, a slab temperature of 10(exp 6,5) K, a field strength of 100 G, and a density ratio of 5. For a slab density of 10(exp 10)/cc, this frequency increases to 8.8/s. Although these frequencies are very high, there in no observational evidence to rule out their existence, and they may be generated both below the corona and at magnetic reconnection sites in the corona. However, we do find that, for slab densities of 10(exp 10)/cc or less, the dissipation of high-frequency waves will be insufficient to balance the radiative losses if the magnetic field strength exceeds roughly 200 G. Because the magnetic field is known to exceed 200 G in many active region loops, particularly low-lying loops and loops emanating from sunspots, it is unlikely that high-frequency waves can provide sufficient heating in these regions.

  2. Field Measurements of Heating Efficiency of Electric Forced-Air Furnaces in Six Manufactured Homes.

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Bob; Palmiter, Larry S.; Siegel, Jeff

    1994-07-26

    This report presents the results of field measurements of heating efficiency for six manufactured homes in the Pacific Northwest heated with electric forced-air systems. This is the first in a series of regional and national efforts to measure in detail the heating efficiency of manufactured homes. Only six homes were included in this study because of budgetary constraints; therefore this is not a representative sample. These investigations do provide some useful information on the heating efficiency of these homes. Useful comparisons can be drawn between these study homes and site-built heating efficiencies measured with a similar protocol. The protocol used to test these homes is very similar to another Ecotope protocol used in the study conducted in 1992 and 1993 for the Bonneville Power Administration to test the heating efficiency of 24 homes. This protocol combined real-time power measurements of furnace energy usage with energy usage during co-heat periods. Accessory data such as house and duct tightness measurements and tracer gas measurements were used to describe these homes and their heating system efficiency. Ensuring that manufactured housing is constructed in an energy and resource efficient manner is of increasing concern to manufactured home builders and consumers. No comparable work has been done to measure the heating system efficiency of MCS manufactured homes, although some co-heat tests have been performed on manufactured homes heated with natural gas to validate HUD thermal standards. It is expected that later in 1994 more research of this kind will be conducted, and perhaps a less costly and less time-consuming method for testing efficiencies will be develops.

  3. Generation of large scale field-aligned density irregularities in ionospheric heating experiments. [electromagnetic wave decay

    Science.gov (United States)

    Fejer, J. A.

    1974-01-01

    Threshold and growth rate for stimulated Brillouin scattering are calculated for a uniform magnetoplasma. These are then compared with the threshold and growth rate of a new thermal instability in which the nonlinear Lorentz force felt by the electrons at the beat frequency of the two electromagnetic waves is replaced by a pressure force due to differential heating in the interference pattern of the pump wave and the generated electromagnetic wave. This thermal instability, which is still essentially stimulated Brillouin scattering, has a threshold which is especially low when the propagation vector of the beat wave is almost normal to the magnetic field. The threshold is then considerably lower than the threshold for normal stimulated Brillouin scattering and therefore this new instability is probably responsible for the generation of large scale field aligned irregularities and ionospheric spread F.

  4. Thermal transport in shock wave-compressed solids using pulsed laser heating.

    Science.gov (United States)

    La Lone, B M; Capelle, G; Stevens, G D; Turley, W D; Veeser, L R

    2014-07-01

    A pulsed laser heating method was developed for determining thermal transport properties of solids under shock-wave compression. While the solid is compressed, a laser deposits a known amount of heat onto the sample surface, which is held in the shocked state by a transparent window. The heat from the laser briefly elevates the surface temperature and then diffuses into the interior via one-dimensional heat conduction. The thermal effusivity is determined from the time history of the resulting surface temperature pulse, which is recorded with optical pyrometry. Thermal effusivity is the square root of the product of thermal conductivity and volumetric heat capacity and is the key thermal transport parameter for relating the surface temperature to the interior temperature of the sample in a dynamic compression experiment. Therefore, this method provides information that is needed to determine the thermodynamic state of the interior of a compressed metal sample from a temperature measurement at the surface. The laser heat method was successfully demonstrated on tin that was shock compressed with explosives to a stress and temperature of ~25 GPa and ~1300 K. In this state, tin was observed to have a thermal effusivity of close to twice its ambient value. The implications on determining the interior shock wave temperature of tin are discussed.

  5. The effect of induced heat waves on Pinus taeda and Quercus rubra seedlings in ambient and elevated CO2 atmospheres.

    Science.gov (United States)

    Ameye, Maarten; Wertin, Timothy M; Bauweraerts, Ingvar; McGuire, Mary Anne; Teskey, Robert O; Steppe, Kathy

    2012-10-01

    Here, we investigated the effect of different heat-wave intensities applied at two atmospheric CO2 concentrations ([CO2]) on seedlings of two tree species, loblolly pine (Pinus taeda) and northern red oak (Quercus rubra). Seedlings were assigned to treatment combinations of two levels of [CO2] (380 or 700 μmol mol(-1)) and four levels of air temperature (ambient, ambient +3°C, or 7-d heat waves consisting of a biweekly +6°C heat wave, or a monthly +12°C heat wave). Treatments were maintained throughout the growing season, thus receiving equal heat sums. We measured gas exchange and fluorescence parameters before, during and after a mid-summer heat wave. The +12°C heat wave, significantly reduced net photosynthesis (Anet) in both species and [CO2] treatments but this effect was diminished in elevated [CO2]. The decrease in Anet was accompanied by a decrease in Fv'/Fm' in P. taeda and ΦPSII in Q. rubra. Our findings suggest that, if soil moisture is adequate, trees will experience negative effects in photosynthetic performance only with the occurrence of extreme heat waves. As elevated [CO2] diminished these negative effects, the future climate may not be as detrimental to plant communities as previously assumed. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

  6. High Efficiency R-744 Commercial Heat Pump Water Heaters

    Energy Technology Data Exchange (ETDEWEB)

    Elbel, Dr. Stefan W.; Petersen, Michael

    2013-04-25

    The project investigated the development and improvement process of a R744 (CO2) commercial heat pump water heater (HPWH) package of approximately 35 kW. The improvement process covered all main components of the system. More specific the heat exchangers (Internal heat exchanger, Evaporator, Gas cooler) as well as the expansion device and the compressor were investigated. In addition, a comparison to a commercially available baseline R134a unit of the same capacity and footprint was made in order to compare performance as well as package size reduction potential.

  7. Preferential Heating of Oxygen 5+ Ions by Finite-Amplitude Oblique Alfven Waves

    Science.gov (United States)

    Maneva, Yana G.; Vinas, Adolfo; Araneda, Jamie; Poedts, Stefaan

    2016-01-01

    Minor ions in the fast solar wind are known to have higher temperatures and to flow faster than protons in the interplanetary space. In this study we combine previous research on parametric instability theory and 2.5D hybrid simulations to study the onset of preferential heating of Oxygen 5+ ions by large-scale finite-amplitude Alfven waves in the collisionless fast solar wind. We consider initially non-drifting isotropic multi-species plasma, consisting of isothermal massless fluid electrons, kinetic protons and kinetic Oxygen 5+ ions. The external energy source for the plasma heating and energization are oblique monochromatic Alfven-cyclotron waves. The waves have been created by rotating the direction of initial parallel pump, which is a solution of the multi-fluid plasma dispersion relation. We consider propagation angles theta less than or equal to 30 deg. The obliquely propagating Alfven pump waves lead to strong diffusion in the ion phase space, resulting in highly anisotropic heavy ion velocity distribution functions and proton beams. We discuss the application of the model to the problems of preferential heating of minor ions in the solar corona and the fast solar wind.

  8. Unsteady Heat-Flux Measurements of Second-Mode Instability Waves in a Hypersonic Boundary Layer

    Science.gov (United States)

    Kergerise, Michael A.; Rufer, Shann J.

    2016-01-01

    In this paper we report on the application of the atomic layer thermopile (ALTP) heat- flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are in agreement with data previously reported in the literature. Heat flux time series, and the Morlet-wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was developed to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.

  9. Exploring the role of Alfvén waves in heating the solar corona

    Science.gov (United States)

    Bose, Sayak; Gekelman, W.; Hahn, M.; Vincena, S.; Savin, D. W.

    2017-10-01

    The solar corona, the outer atmosphere of the Sun, is 200 times hotter than the underlying visible surface of the Sun. Recent coronal observations find Alfvén wave damping at unexpectedly low heights in the corona, suggesting that Alfvén waves may contribute to the heating of the corona to temperatures of 106 K. Dissipation of wave energy may occur due to gradients in the Alfvén speed along the coronal magnetic field lines. These gradients may cause wave reflection, which subsequently generates turbulence. Furthermore, the presence of gradients in the Alfvén speed across the magnetic field line may lead to phase mixing, which can promote additional nonlinear damping mechanisms. We are studying various wave dissipation processes under conditions similar to the solar corona, using the Large Plasma Device (LAPD) at the University of California, at Los Angeles. Here we will present the results of our initial experiments exploring the effectiveness of gradients in the Alfvén speed along the magnetic field in reflecting Alfvén waves and reducing the amplitude of Alfvén waves transmitted across a gradient. This work is supported, in part, by the DoE, NSF, and NASA. The Basic Plasma Science facility is supported by the DoE OFES and the NSF.

  10. Highly efficient proteolysis accelerated by electromagnetic waves for Peptide mapping.

    Science.gov (United States)

    Chen, Qiwen; Liu, Ting; Chen, Gang

    2011-09-01

    Proteomics will contribute greatly to the understanding of gene functions in the post-genomic era. In proteome research, protein digestion is a key procedure prior to mass spectrometry identification. During the past decade, a variety of electromagnetic waves have been employed to accelerate proteolysis. This review focuses on the recent advances and the key strategies of these novel proteolysis approaches for digesting and identifying proteins. The subjects covered include microwave-accelerated protein digestion, infrared-assisted proteolysis, ultraviolet-enhanced protein digestion, laser-assisted proteolysis, and future prospects. It is expected that these novel proteolysis strategies accelerated by various electromagnetic waves will become powerful tools in proteome research and will find wide applications in high throughput protein digestion and identification.

  11. On the existence of motion-induced heat flux due to thermoelastic waves in a one-dimensional solid rod

    Science.gov (United States)

    Semperlotti, Fabio; Sen, Mihir

    2014-03-01

    In this Letter, we show the existence of motion-induced heat transfer in homogeneous isotropic solids due to the propagation of thermoelastic waves. In particular, using the linearized governing equations for thermoelastic waves, we show that heat transfer in a one-dimensional rod is not only due to conduction but also to the local particle displacement a phenomenon which, in principle, is similar to advective heat transfer in fluids. It is found that the time-averaged heat transfer is dependent on both the material properties and the external excitation parameters. This mechanism can potentially be useful in ultrasonic welding and in the development of solid state refrigerators or heat pumps.

  12. An efficient wave extrapolation method for anisotropic media with tilt

    KAUST Repository

    Waheed, Umair bin

    2015-03-23

    Wavefield extrapolation operators for elliptically anisotropic media offer significant cost reduction compared with that for the transversely isotropic case, particularly when the axis of symmetry exhibits tilt (from the vertical). However, elliptical anisotropy does not provide accurate wavefield representation or imaging for transversely isotropic media. Therefore, we propose effective elliptically anisotropic models that correctly capture the kinematic behaviour of wavefields for transversely isotropic media. Specifically, we compute source-dependent effective velocities for the elliptic medium using kinematic high-frequency representation of the transversely isotropic wavefield. The effective model allows us to use cheaper elliptic wave extrapolation operators. Despite the fact that the effective models are obtained by matching kinematics using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy trade-off for wavefield computations in transversely isotropic media, particularly for media of low to moderate complexity. In addition, the wavefield solution is free from shear-wave artefacts as opposed to the conventional finite-difference-based transversely isotropic wave extrapolation scheme. We demonstrate these assertions through numerical tests on synthetic tilted transversely isotropic models.

  13. Hybrid Model of Inhomogeneous Solar Wind Plasma Heating by Alfven Wave Spectrum: Parametric Studies

    Science.gov (United States)

    Ofman, L.

    2010-01-01

    Observations of the solar wind plasma at 0.3 AU and beyond show that a turbulent spectrum of magnetic fluctuations is present. Remote sensing observations of the corona indicate that heavy ions are hotter than protons and their temperature is anisotropic (T(sub perpindicular / T(sub parallel) >> 1). We study the heating and the acceleration of multi-ion plasma in the solar wind by a turbulent spectrum of Alfvenic fluctuations using a 2-D hybrid numerical model. In the hybrid model the protons and heavy ions are treated kinetically as particles, while the electrons are included as neutralizing background fluid. This is the first two-dimensional hybrid parametric study of the solar wind plasma that includes an input turbulent wave spectrum guided by observation with inhomogeneous background density. We also investigate the effects of He++ ion beams in the inhomogeneous background plasma density on the heating of the solar wind plasma. The 2-D hybrid model treats parallel and oblique waves, together with cross-field inhomogeneity, self-consistently. We investigate the parametric dependence of the perpendicular heating, and the temperature anisotropy in the H+-He++ solar wind plasma. It was found that the scaling of the magnetic fluctuations power spectrum steepens in the higher-density regions, and the heating is channeled to these regions from the surrounding lower-density plasma due to wave refraction. The model parameters are applicable to the expected solar wind conditions at about 10 solar radii.

  14. Heat rejection and thermal efficiency in model hydrogen-halogen fuel cell systems

    Energy Technology Data Exchange (ETDEWEB)

    Balko, E.N.

    1981-01-01

    The efficiency and heat rejection characteristics of the H/sub 2//Cl/sub 2/, H/sub 2//Br/sub 2/ and H/sub 2//I/sub 2/ fuel cell systems have been studied. The H/sub 2//Cl/sub 2/ and H/sub 2//Br/sub 2/ systems are comparable in terms of efficiency, heat rejection and fuel mass. The H/sub 2//I/sub 2/ system is markedly less efficient.

  15. Analysis of efficient preconditioned defect correction methods for nonlinear water waves

    DEFF Research Database (Denmark)

    Engsig-Karup, Allan Peter

    2014-01-01

    Robust computational procedures for the solution of non-hydrostatic, free surface, irrotational and inviscid free-surface water waves in three space dimensions can be based on iterative preconditioned defect correction (PDC) methods. Such methods can be made efficient and scalable to enable...... prediction of free-surface wave transformation and accurate wave kinematics in both deep and shallow waters in large marine areas or for predicting the outcome of experiments in large numerical wave tanks. We revisit the classical governing equations are fully nonlinear and dispersive potential flow...... equations. We present new detailed fundamental analysis using finite-amplitude wave solutions for iterative solvers. We demonstrate that the PDC method in combination with a high-order discretization method enables efficient and scalable solution of the linear system of equations arising in potential flow...

  16. Air pollution during the 2003 European heat wave as seen by MOZAIC airliners

    Directory of Open Access Journals (Sweden)

    M. Tressol

    2008-04-01

    Full Text Available This study presents an analysis of both MOZAIC profiles above Frankfurt and Lagrangian dispersion model simulations for the 2003 European heat wave. The comparison of MOZAIC measurements in summer 2003 with the 11-year MOZAIC climatology reflects strong temperature anomalies (exceeding 4°C throughout the lower troposphere. Higher positive anomalies of temperature and negative anomalies of both wind speed and relative humidity are found for the period defined here as the heat wave (2–14 August 2003, compared to the periods before (16–31 July 2003 and after (16–31 August 2003 the heat wave. In addition, Lagrangian model simulations in backward mode indicate the suppressed long-range transport in the mid- to lower troposphere and the enhanced southern origin of air masses for all tropospheric levels during the heat wave. Ozone and carbon monoxide also present strong anomalies (both ~+40 ppbv during the heat wave, with a maximum vertical extension reaching 6 km altitude around 11 August 2003. Pollution in the planetary boundary layer (PBL is enhanced during the day, with ozone mixing ratios two times higher than climatological values. This is due to a combination of factors, such as high temperature and radiation, stagnation of air masses and weak dry deposition, which favour the accumulation of ozone precursors and the build-up of ozone. A negligible role of a stratospheric-origin ozone tracer has been found for the lower troposphere in this study. From 29 July to 15 August 2003 forest fires burnt around 0.3×106 ha in Portugal and added to atmospheric pollution in Europe. Layers with enhanced CO and NOy mixing ratios, advected from Portugal, were crossed by the MOZAIC aircraft in the free troposphere over Frankfurt. A series of forward and backward Lagrangian model simulations have been performed to investigate the origin of anomalies during the whole heat wave. European anthropogenic emissions present the strongest

  17. Projection of heat waves variation over a warming climate in China

    Science.gov (United States)

    Yue, X.; Wu, S.; Pan, T.

    2016-12-01

    Heat waves (HW) have adverse impacts on economies, human health, societies and environment, which have been observed around the world and are expected to increase in a warming climate. However, the variations of HW under climate change over China are not clear yet. Using the HadGEM2-ES RCP4.5 and RCP8.5 daily maximum temperature and humidity dataset, variation of heat waves in China for 2021-2050 comparing to 1991-2000 as baseline were analyzed. The CMA-HI (Heat Index standardized by China Meteorological Administration) index was used to calculate the frequency and intensity of head waves. This paper classified the HW into three intensity levels including mild HW, moderate HW and severe HW , and defined a heat wave event (HWE) as that CMA-HI are all above or equal to 2.8 and keep at a intensity level more than five consecutive days. Results show that during 2021to 2050, the distribution area, frequency and duration of each intensity level have an increasing trend over China, and those of severe HW will increase mostly. The distribution area of mild, moderate and severe HW will increase 18%, 22%, 35% respectively. Average HWE frequency of each level will concentrate on 0.5-1instead of 0-0.3 in baseline period. Maximum frequency of each intensity can reach to almost 3 times a year. During 1991-2000, the average frequency of mild HW, moderate HW and severe HW kept a downward sequence. But it will change to increase in the future, and the shift occurs during 2031-2040. In addition, only severe HW duration will increase in the future. Its average value will increase from 9days to 13days, and keep a maximum duration of 42days.While the average duration of mild HW and moderate HW just keep almost 6 days and 8 days as usual. Regionally, both the frequency and duration will keep high value in the region of eastern China, central China, southern China and central Xinjiang autonomous region in the future. And only severe HW has a great change in distribution. Under RCP 8

  18. Heat-stop structure design with high cooling efficiency for large ground-based solar telescope.

    Science.gov (United States)

    Liu, Yangyi; Gu, Naiting; Rao, Changhui; Li, Cheng

    2015-07-20

    A heat-stop is one of the most important thermal control devices for a large ground-based solar telescope. For controlling the internal seeing effect, the temperature difference between the heat-stop and the ambient environment needs to be reduced, and a heat-stop with high cooling efficiency is required. In this paper, a novel design concept for the heat-stop, in which a multichannel loop cooling system is utilized to obtain higher cooling efficiency, is proposed. To validate the design, we analyze and compare the cooling efficiency for the multichannel and existing single-channel loop cooling system under the same conditions. Comparative results show that the new design obviously enhances the cooling efficiency of the heat-stop, and the novel design based on the multichannel loop cooling system is obviously better than the existing design by increasing the thermal transfer coefficient.

  19. Conversion efficiency of an energy harvester based on resonant tunneling through quantum dots with heat leakage.

    Science.gov (United States)

    Kano, Shinya; Fujii, Minoru

    2017-03-03

    We study the conversion efficiency of an energy harvester based on resonant tunneling through quantum dots with heat leakage. Heat leakage current from a hot electrode to a cold electrode is taken into account in the analysis of the harvester operation. Modeling of electrical output indicates that a maximum heat leakage current is not negligible because it is larger than that of the heat current harvested into electrical power. A reduction of heat leakage is required in this energy harvester in order to obtain efficient heat-to-electrical conversion. Multiple energy levels of a quantum dot can increase the output power of the harvester. Heavily doped colloidal semiconductor quantum dots are a possible candidate for a quantum-dot monolayer in the energy harvester to reduce heat leakage, scaling down device size, and increasing electrical output via multiple discrete energy levels.

  20. The effectiveness of absorption heat pumps application for the increase of economic efficiency of CHP operation

    Directory of Open Access Journals (Sweden)

    Luzhkovoy Dmitriy S.

    2017-01-01

    Full Text Available The article deals with a comparative analysis of CHP operational efficiency in various working modes before and after the absorption heat pumps installation. The calculation was performed using a mathematical model of the extraction turbine PT- 80/100-130/13. Absorption heat pumps of LLC “OKB Teplosibmash” were used as AHP models for the analysis. The most effective way of absorption lithium-bromide heat pumps application as a part of the turbine PT-80/100-130/13 turned out to be their usage in a heat-producing mode during a non-heating season with a load of hot water supply. For this mode the dependence of the turbine heat efficiency on the heat load of the external consumer at a given throttle flow was analyzed.

  1. Multiple tube structure for heating uniformity and efficiency optimization of microwave ovens

    Science.gov (United States)

    Zhou, Rong; Yang, Xiaoqing; Sun, Di; Jia, Guozhu

    2015-02-01

    Microwave heating is widely applied to microwave assisted chemical reactions in modified domestic microwave ovens, however, the potential issues (non-uniformity and low heating efficiency) still exist during the heating process. In this paper, a new heating model of multiple tube structure is proposed and the relevant simulations and experiments of heating water were performed based on the computational platform COMSOL Multi-physics software in order to achieve the better temperature uniformity and heating efficiency. Besides, the influence of the instability of microwave ovens on the heating performances of the optimal heating models was analyzed. The simulation results show that the heating uniformity and efficiency of water in optimal six tube structure increased by 7.1% and 68.5% (30 mL), 9.2% and 61% (60 mL) respectively compared with the optimal single tube structure. Moreover, the heating performances of the optimal heating models do not change obviously, while the working frequency and power change slightly. The simulation results are in good agreement with the experiment data.

  2. Predicting observational signatures of coronal heating by Alfvén waves and Nanoflares

    Science.gov (United States)

    Antolin, Patrick

    2009-09-01

    The subject of this thesis is the coronal heating problem, a long standing problem not only in solar physics but in astrophysics, since it is addressed to all stars that possess a corona. The Sun, a middle aged main sequence star of class G2V, has been unveiling many mysteries to us in the last century, especially since the advent of the space era. More than 70 years ago a very hot temperature component in the corona was discovered, reaching temperatures as high as a few million degrees. Such a hot corona came as a surprise to astrophysicists, since it seemed to contradict the second law of thermodynamics being 200 times hotter than the underlying photosphere, the source of its energy. Since then the coronal heating problem has spawned an active research community in solar physics that aims to unveil yet another mystery. This thesis has as purpose to shed some light into the fascinating subject of coronal heating. In the first chapter we give an introduction to the field, in which we discuss the main heating candidate mechanisms: Alfvén wave heating and nanoflare-reconnection heating. Predicting unique observational signatures of each heating mechanism which would allow their distinction during observations is the main purpose of this thesis and the subject of the second chapter. In this chapter we investigate the thermodynamic properties of a corona in a magnetic flux tube obtained, separately, with the two heating mechanisms. We derive a series of observational features which may allow the clear distinction between the two heating mechanisms during observations. In chapter 3 we further investigate the role of Alfvén wave heating in the solar atmosphere. We concentrate our study on magnetic flux tubes (loops), which are closed magnetic structures which populate the solar atmosphere. In the considered model Alfvén waves are generated at the footpoints of a loop and can dissipate their energy mainly through the mode conversion mechanism. A parameter survey is

  3. Technical-and-Economic Efficiency of Draft Enriched with Oxygen in Small-Capacity Heating Boilers

    Directory of Open Access Journals (Sweden)

    P. Ratnikov

    2013-01-01

    Full Text Available Data on complex experimental and theoretical investigations pertaining to efficiency of oxygen-enriched draft in the small-capacity heating boilers as exemplified by the plant HEIZA (HW-S-10/K have been presented in the paper. The paper provides a calculation model of heating processes in heat generator burner (as exemplified by HEIZA plant. Simulation of heating processes in the operational zone has been executed in paper. The experimental data have proved model adequacy. The calculation scheme of the plant will be used in future for determination of power and ecological efficiency of draft enrichment with oxygen.

  4. Comprehensive Assessment of the Potential for Efficient District Heating and Cooling and for High-Efficient Cogeneration in Austria

    Directory of Open Access Journals (Sweden)

    Richard Büchele

    2016-12-01

    Full Text Available In accordance with the EU Energy Efficiency Directive all Member States have to develop a comprehensive assessment of the potential for high-efficient CHP and efficient district heating and cooling by the end of 2015. This paper describes the approach and methodology used to determine the district heating potentials for Austria. In a first step actual and future heating and cooling demand in the building sector is evaluated using the techno-economic bottom-up model Invert/EE-Lab. Relevant infrastructure probably existing in 2025 is investigated and included into the analysis. Technical potentials for efficient technologies are calculated. After a classification of relevant regions into main and secondary regions a country-level cost-benefit-analysis is performed. The results indicate that there is a reasonable additional potential for district heating by the year 2025 under our central scenario assumptions and within sensitivity scenarios. Only in scenarios with high CO2-price or low gas price, CHP is an economically efficient solution to supply district heat.

  5. Efficient solar water heating system for a public building

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, P.E.; Lange, M.

    1986-01-01

    In the municipality of Roedovre, West of Copenhagen, an 18 m/sup 2/ solar water heating system has been installed at a building for municipal employers working with maintenance of roads, snow clearing etc. The hot water system for the building originally consisted of a 1500 l domestic hot water (DHW) tank, heated from an oilfired boiler serving both space heating and DHW production. The performance of the system has been monitored for almost one year. The results of the measurements indicates an output from the solar system at app. 375 kWh/m/sup 2/ pr. year (total app. 6760 kWh). In adition to this a considerably reduction in the oil consumption has been obtained by turning off the oilfired boiler in the summer period. The total reduction in oilconsumption in the first year is measured to app. 38,700 kWh and the extra use of electricity has been 4486 kWh.

  6. Calculation of critical efficiency factors of microwave energy conversion into heat

    Energy Technology Data Exchange (ETDEWEB)

    Cherbanski, R. [Warsaw University of Technology, Chemical and Process Engineering Department, Warszawa (Poland)

    2011-12-15

    A modeling approach aimed at calculating critical efficiency factors of microwave energy conversion into heat for different operating conditions is presented. In the experimental part, an efficiency factor was determined for microwave heating of 13X zeolites in a multimode microwave cavity. A comparison of the obtained results with the results reported in the literature indicated that microwave heating (MH) can be more energy-efficient than convective heating (CH). Moreover, it follows from the performed simulations that maintaining the same adsorbent bed temperatures in MH and CH for increasing gas flow rates rises energy consumptions in CH and decreases the critical efficiency factors, thereby improving the economic efficiency of MH. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. Simultaneous excitation system for efficient guided wave structural health monitoring

    Science.gov (United States)

    Hua, Jiadong; Michaels, Jennifer E.; Chen, Xin; Lin, Jing

    2017-10-01

    Many structural health monitoring systems utilize guided wave transducer arrays for defect detection and localization. Signals are usually acquired using the ;pitch-catch; method whereby each transducer is excited in turn and the response is received by the remaining transducers. When extensive signal averaging is performed, the data acquisition process can be quite time-consuming, especially for metallic components that require a low repetition rate to allow signals to die out. Such a long data acquisition time is particularly problematic if environmental and operational conditions are changing while data are being acquired. To reduce the total data acquisition time, proposed here is a methodology whereby multiple transmitters are simultaneously triggered, and each transmitter is driven with a unique excitation. The simultaneously transmitted waves are captured by one or more receivers, and their responses are processed by dispersion-compensated filtering to extract the response from each individual transmitter. The excitation sequences are constructed by concatenating a series of chirps whose start and stop frequencies are randomly selected from a specified range. The process is optimized using a Monte-Carlo approach to select sequences with impulse-like autocorrelations and relatively flat cross-correlations. The efficacy of the proposed methodology is evaluated by several metrics and is experimentally demonstrated with sparse array imaging of simulated damage.

  8. Microwave pre-heating of natural rubber using a rectangular wave guide (MODE: TE10

    Directory of Open Access Journals (Sweden)

    Doo-ngam, N.

    2007-11-01

    Full Text Available This paper presents an application of microwave radiation for pre-heating of natural rubbercompounding with various sulphur contents. The natural rubber-compounding was pre-heated by microwave radiation using a rectangular wave guide system (MODE: TE10 operating at frequency of 2.45 GHz in which the power can vary from 0 to 1500 W. In the present work, the influence of power input, sample thickness, and sulphur content were examined after applying microwave radiation to the rubber samples. Results are discussed regarding the thermal properties, 3-D network, dielectric properties and chemical structures. From the result, firstly, it was found that microwave radiation can be applied to pre-heating natural rubber-compounding before the vulcanization process. Secondly, microwave radiation was very useful for pre-heating natural rubber-compounding that has a thickness greater than 5mm. Thirdly, crosslinking in natural rubber-compounding may occurs after pre-heating by microwave radiation though Fourier Transform Infrared Spectroscopy(FTIR. Finally, there a little effect of sulphur content on temperature profiles after applying microwave radiation to the natural rubber-compounding. Moreover, natural rubber-compounding without carbon black showed a lower heat absorption compared with natural rubbercompounding filled carbon black. This is due to the difference in dielectric loss factor. This preliminary result will be useful information in terms of microwave radiation for pre-heating natural rubber-compounding and rubber processing in industry.

  9. The role of Ekman flow and planetary waves in the oceanic cross-equatorial heat transport

    Science.gov (United States)

    Schopf, P. S.

    1980-01-01

    A numerical model is used to mechanistically simulate the oceans' seasonal cross-equatorial heat transport. The basic process of Ekman pumping and drift is able to account for a large amount of the cross-equatorial flux. Increased easterly wind stress in the winter hemisphere causes Ekman surface drift poleward, while decreased easterly stress allows a reduction in the poleward drift in the summer hemisphere. The addition of planetary and gravity waves to this model does not alter the net cross-equatorial flow, although the planetary waves are clearly seen. On comparison with Oort and Vonder Haar (1976), this adiabatic advective redistribution of heat is seen to be plausible up to 10-20 deg N, beyond which other dynamics and thermodynamics are indicated.

  10. Exposure to a heat wave under food limitation makes an agricultural insecticide lethal: a mechanistic laboratory experiment

    DEFF Research Database (Denmark)

    Dinh, Khuong Van; Janssens, Lizanne; Stoks, Robby

    2016-01-01

    variables. While the immediate effects of the heat wave were subtle, our results indicate the importance of delayed effects in shaping the total fitness impact of a heat wave when followed by pesticide exposure. Firstly, the combination of delayed negative effects of the heat wave and starvation...... for mortality could be explained by the cumulative metabolic depression caused by each of these stressors. Further studies with increased realism are needed to evaluate the consequences of the here-identified delayed synergisms at the level of populations and communities. This is especially important...

  11. Modeling heat efficiency, flow and scale-up in the corotating disc scraped surface heat exchanger

    DEFF Research Database (Denmark)

    Friis, Alan; Szabo, Peter; Karlson, Torben

    2002-01-01

    A comparison of two different scale corotating disc scraped surface heat exchangers (CDHE) was performed experimentally. The findings were compared to predictions from a finite element model. We find that the model predicts well the flow pattern of the two CDHE's investigated. The heat transfer...... performance predicted by the model agrees well with experimental observations for the laboratory scale CDHE whereas the overall heat transfer in the scaled-up version was not in equally good agreement. The lack of the model to predict the heat transfer performance in scale-up leads us to identify the key...

  12. CO2 and Energy Efficiency of Different Heating Technologies in the Dutch Glasshouse Industry

    Energy Technology Data Exchange (ETDEWEB)

    Oude Lansink, A. [Wageningen University, Department of Social Sciences, Hollandseweg 1, 6706 KN Wageningen (Netherlands); Silva, E. [University of Porto, Faculty of Economics, CETE (Portugal)

    2003-04-01

    This paper uses Data Envelopment Analysis to compute input-based technical efficiency measures and CO2 and energy technical efficiency of specialised vegetable firms in the Netherlands over the period 1991-1995. Input-based scale efficiency is also calculated for each firm. These efficiency measures are generated for firms with different heating technologies. The empirical results indicate that firms use energy quite efficiently and are less efficient in terms of CO2 emissions. Differences in CO2 (energy) efficiency across different technologies are (not) statistically significant. In particular, firms using traditional heating technologies are less efficient in terms of CO2. Scale adjustments can provide an important contribution to further efficiency improvements.

  13. Optimising Reactive Control in non-ideal Efficiency Wave Energy Converters

    DEFF Research Database (Denmark)

    Strager, Thomas; Lopez, Pablo Fernandez; Giorgio, Giuseppe

    2014-01-01

    . These have been derived under the assumptions of monochromatic incoming waves and linear system behaviour. This allows to establish the power factor of a system with non-ideal efficiency. The locus of the optimal reactive control parameters is then studied and an alternative method of representation......When analytically optimising the control strategy in wave energy converters which use a point absorber, the efficiency aspect is generally neglected. The results presented in this paper provide an analytical expression for the mean harvested electrical power in non-ideal efficiency situations...... is developed to model the optimal control parameters. Ultimately we present a simple method of choosing optimal control parameters for any combination of efficiency and wave frequency....

  14. Investigation of Heat Sink Efficiency for Electronic Component Cooling Applications

    DEFF Research Database (Denmark)

    Staliulionis, Ž.; Zhang, Zhe; Pittini, Riccardo

    2014-01-01

    of relatively simple heat sink application is performed using modeling based on finite element method, and also the potential of such analysis was demonstrated by real-world measurements and comparing obtained results. Thermal modeling was accomplished using finite element analysis software COMSOL and thermo...

  15. Anomalies of hydrological cycle components during the 2007 heat wave in Bulgaria

    Science.gov (United States)

    Mircheva, Biliana; Tsekov, Milen; Meyer, Ulrich; Guerova, Guergana

    2017-12-01

    Heat waves have large adverse social, economic and environmental effects which include increased mortality, transport restrictions and a decreased agricultural production. The estimated economic losses of the 2007 heat wave in South-east Europe exceed 2 billion EUR with 19 000 hospitalisation in Romania only. Understanding the changes of the hydrological cycle components is essential for early forecasting of heat wave occurrence. Valuable insight of two components of the hydrological cycle, namely Integrated Water Vapour (IWV) and Terrestrial Water Storage Anomaly (TWSA), is now possible using observations from Global Navigation Satellite System (GNSS) and Gravity Recovery And Climate Experiment (GRACE) mission. In this study anomalies of temperature, precipitation, IWV and TWS in 2007 are compared to 2003-2013 period for Sofia, Bulgaria. In 2007, positive temperature anomalies are observed in January, February and July. There are negative IWV and precipitation anomalies in July 2007 that coincides with the heat wave in Bulgaria. TWSA in 2007 are negative in January, May and from July to October being largest in August. Long-term trends of: 1) temperatures have a local maximum in March 2007, 2) TWSA has a local minimum in May 2007, 3) IWV has a local minimum in September 2007, and 4) precipitation has a local maximum in July 2007. The TWSA interannual trends in Bulgaria, Hungary and Poland show similar behaviour as indicated by cross correlation coefficients of 0.9 and 0.7 between Bulgaria and Hungary and Bulgaria and Poland respectively. ALADIN-Climate describes the anomalies of temperature and IWV more successfully than those of precipitation and TWS.

  16. Energy efficient multistage zeolite drying for heat sensitive products

    NARCIS (Netherlands)

    Djaeni, M.

    2008-01-01

    Although drying takes a significant part of the total energy usage in industry, currently available drying technology is often not efficient in terms of energy consumption. Generally, the energy efficiency for drying processes ranges between 20-60% depending on the dryer type and product to be

  17. Heat waves reduce ecosystem carbon sink strength in a Eurasian meadow steppe.

    Science.gov (United States)

    Qu, Luping; Chen, Jiquan; Dong, Gang; Jiang, Shicheng; Li, Linghao; Guo, Jixun; Shao, Changliang

    2016-01-01

    As a consequence of global change, intensity and frequency of extreme events such as heat waves (HW) have been increasing worldwide. By using a combination of continuous 60-year meteorological and 6-year tower-based carbon dioxide (CO2) flux measurements, we constructed a clear picture of a HWs effect on the dynamics of carbon, water, and vegetation on the Eurasian Songnen meadow steppe. The number of HWs in the Songnen meadow steppe began increasing since the 1980s and the rate of occurrence has advanced since the 2010s to higher than ever before. HWs can reduce the grassland carbon flux, while net ecosystem carbon exchange (NEE) will regularly fluctuate for 4-5 days during the HW before decreasing. However, ecosystem respiration (Re) and gross ecosystem production (GEP) decline from the beginning of the HW until the end, where Re and GEP will decrease 30% and 50%, respectively. When HWs last five days, water-use efficiency (WUE) will decrease by 26%, soil water content (SWC) by 30% and soil water potential (SWP) will increase by 38%. In addition, the soil temperature will still remain high after the HW although the air temperature will recover to its previous state. HWs, as an extreme weather event, have increased during the last two decades in the Songnen meadow steppe. HWs will reduce the carbon flux of the steppe and will cause a sustained impact. Drought may be the main reason why HWs decrease carbon flux. At the later stages of or after a HW, the ecosystem usually lacks water and the soil becomes so hot and dry that it prevents roots from absorbing enough water to maintain their metabolism. This is the main reason why this grassland carbon exchange decreases during and after HWs. Copyright © 2015 Elsevier Inc. All rights reserved.

  18. Analysis of the efficiency of a hybrid foil tunnel heating system

    Science.gov (United States)

    Kurpaska, Sławomir; Pedryc, Norbert

    2017-10-01

    The paper analyzes the efficiency of the hybrid system used to heat the foil tunnel. The tested system was built on the basis of heat gain in a cascade manner. The first step is to heat the water in the storage tank using the solar collectors. The second stage is the use of a heat pump (HP) in order to heat the diaphragm exchangers. The lower HP heat source is a cascade first stage buffer. In the storage tank, diaphragm exchangers used for solar collectors and heat pumps are installed. The research was carried out at a research station located in the University of Agriculture in Cracow. The aim was to perform an analysis of the efficiency of a hybrid system for the heating of a foil tunnel in the months from May to September. The efficiency of the entire hybrid system was calculated as the relation of the effect obtained in reference to the electrical power used to drive the heat pump components (compressor drive, circulation pump), circulation pumps and fans installed in the diaphragm heaters. The resulting effect was the amount of heat supplied to the interior of the object as a result of the internal air being forced through the diaphragm exchangers.

  19. Analysis of the efficiency of a hybrid foil tunnel heating system

    Directory of Open Access Journals (Sweden)

    Kurpaska Sławomir

    2017-01-01

    Full Text Available The paper analyzes the efficiency of the hybrid system used to heat the foil tunnel. The tested system was built on the basis of heat gain in a cascade manner. The first step is to heat the water in the storage tank using the solar collectors. The second stage is the use of a heat pump (HP in order to heat the diaphragm exchangers. The lower HP heat source is a cascade first stage buffer. In the storage tank, diaphragm exchangers used for solar collectors and heat pumps are installed. The research was carried out at a research station located in the University of Agriculture in Cracow. The aim was to perform an analysis of the efficiency of a hybrid system for the heating of a foil tunnel in the months from May to September. The efficiency of the entire hybrid system was calculated as the relation of the effect obtained in reference to the electrical power used to drive the heat pump components (compressor drive, circulation pump, circulation pumps and fans installed in the diaphragm heaters. The resulting effect was the amount of heat supplied to the interior of the object as a result of the internal air being forced through the diaphragm exchangers.

  20. Differences on the effect of heat waves on mortality by sociodemographic and urban landscape characteristics.

    Science.gov (United States)

    Xu, Yihan; Dadvand, Payam; Barrera-Gómez, Jose; Sartini, Claudio; Marí-Dell'Olmo, Marc; Borrell, Carme; Medina-Ramón, Mercè; Sunyer, Jordi; Basagaña, Xavier

    2013-06-01

    Mortality increases during heat waves have been reported worldwide. The magnitude of these increases can vary within regions according to sociodemographic and urban landscape characteristics. The objectives of this study were to explore this variation and its determinants, and to identify the most heat-vulnerable areas by mapping heat vulnerability. We conducted a time-stratified case-crossover analysis using daily mortality in the Barcelona metropolitan area during the warm seasons of 1999-2006. Temperature data on the date of death were assigned to each individual, which were assigned to their census tract of residence. Eight census tract-level variables on socioeconomic or built environment characteristics were obtained from the census. Residence surrounding greenness was obtained from satellite data. The relative risk (RR) of mortality after three consecutive hot days (defined as those exceeding the 95th percentile of maximum temperature) was calculated via conditional logistic regression. Effect modification was examined by including interaction terms. Analyses were based on 52 806 deaths. The effect of three consecutive hot days was a 30% increase in all-cause mortality (RR=1.30, 95% CI 1.24 to 1.38). Heterogeneity of this effect was observed across census tracts. The effect of heat on mortality was higher in the census tracts with a large percentage of old buildings (RR=1.21, 95% CI 1.00 to 1.46), manual workers (RR=1.25, 95% CI 0.96 to 1.64) and residents perceiving little surrounding greenness (RR=1.29, 95% CI 1.01 to 1.65). After three consecutive hot days, mortality doubled in the most heat-vulnerable census tracts. Sociodemographic and urban landscape characteristics are associated to mortality risk during heat waves and are useful to build heat vulnerability maps.

  1. New configurations of a heat recovery absorption heat pump integrated with a natural gas boiler for boiler efficiency improvement

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Ming [Purdue University, West Lafayette, IN; Abdelaziz, Omar [ORNL; Yin, Hongxi [Southeast University, Nanjing, China

    2014-11-01

    Conventional natural gas-fired boilers exhaust flue gas direct to the atmosphere at 150 200 C, which, at such temperatures, contains large amount of energy and results in relatively low thermal efficiency ranging from 70% to 80%. Although condensing boilers for recovering the heat in the flue gas have been developed over the past 40 years, their present market share is still less than 25%. The major reason for this relatively slow acceptance is the limited improvement in the thermal efficiency of condensing boilers. In the condensing boiler, the temperature of the hot water return at the range of 50 60 C, which is used to cool the flue gas, is very close to the dew point of the water vapor in the flue gas. Therefore, the latent heat, the majority of the waste heat in the flue gas, which is contained in the water vapor, cannot be recovered. This paper presents a new approach to improve boiler thermal efficiency by integrating absorption heat pumps with natural gas boilers for waste heat recovery (HRAHP). Three configurations of HRAHPs are introduced and discussed. The three configurations are modeled in detail to illustrate the significant thermal efficiency improvement they attain. Further, for conceptual proof and validation, an existing hot water-driven absorption chiller is operated as a heat pump at operating conditions similar to one of the devised configurations. An overall system performance and economic analysis are provided for decision-making and as evidence of the potential benefits. These three configurations of HRAHP provide a pathway to achieving realistic high-efficiency natural gas boilers for applications with process fluid return temperatures higher than or close to the dew point of the water vapor in the flue gas.

  2. Effect of heat waves on VOC emissions from vegetation and urban air quality

    Science.gov (United States)

    Churkina, G.; Kuik, F.; Lauer, A.; Bonn, B.; Butler, T. M.

    2015-12-01

    Programs to plant millions of trees in cities around the world aim at the reduction of summer temperatures, increase carbon storage, storm water control, provision of space for recreation, as well as poverty alleviation. Although these multiple benefits speak positively for urban greening programs, the programs do not take into account how close human and natural systems are coupled in urban areas. Elevated temperatures together with anthropogenic emissions of air and water pollutants distinguish the urban system. Urban and sub-urban vegetation responds to ambient changes and reacts with pollutants. Neglecting this coupling may lead to unforeseen drawbacks of urban greening programs. The potential for emissions of volatile organic compounds (VOC) from vegetation combined with anthropogenic emissions to produce ozone has long been recognized. This potential increases under rising temperatures. Here we investigate how heat waves affect emissions of VOC from urban vegetation and corresponding ground-level ozone. In this study we use Weather Research and Forecasting Model with coupled atmospheric chemistry (WRF-CHEM) to quantify these feedbacks in Berlin, Germany during the 2006 heat wave. VOC emissions from vegetation are simulated with MEGAN 2.0 coupled with WRF-CHEM. Our preliminary results indicate that contribution of VOCs from vegetation to ozone formation may increase by more than twofold during the heat wave period. We highlight the importance of the vegetation for urban areas under changing climate and discuss associated tradeoffs.

  3. Cool Roofs in Guangzhou, China: Outdoor Air Temperature Reductions during Heat Waves and Typical Summer Conditions.

    Science.gov (United States)

    Cao, Meichun; Rosado, Pablo; Lin, Zhaohui; Levinson, Ronnen; Millstein, Dev

    2015-12-15

    In this paper, we simulate temperature reductions during heat-wave events and during typical summer conditions from the installation of highly reflective "cool" roofs in the Chinese megacity of Guangzhou. We simulate temperature reductions during six of the strongest historical heat-wave events over the past decade, finding average urban midday temperature reductions of 1.2 °C. In comparison, we simulate 25 typical summer weeks between 2004 and 2008, finding average urban midday temperature reductions of 0.8 °C, indicating that air temperature sensitivity to urban albedo in Guangzhou varies with meteorological conditions. We find that roughly three-fourths of the variance in air temperature reductions across all episodes can be accounted for by a linear regression, including only three basic properties related to the meteorological conditions: mean daytime temperature, humidity, and ventilation to the greater Guangzhou urban area. While these results highlight the potential for cool roofs to mitigate peak temperatures during heat waves, the temperature reductions reported here are based on the upper bound case, which increases albedos of all roofs (but does not modify road albedo or wall albedo).

  4. Strong negative effects of simulated heat waves in a tropical butterfly.

    Science.gov (United States)

    Fischer, Klaus; Klockmann, Michael; Reim, Elisabeth

    2014-08-15

    Climate change poses a significant challenge to all natural systems on Earth. Especially increases in extreme weather events such as heat waves have the potential to strongly affect biodiversity, though their effects are poorly understood because of a lack of empirical data. Therefore, we here explore the sensitivity of a tropical ectotherm, which are in general believed to have a low warming tolerance, to experimentally simulated climate change using ecologically realistic diurnal temperature cycles. Increasing the mean temperature permanently by 3°C had mostly minor effects on developmental traits in the butterfly Bicyclus anynana. Simulated heat waves (strongly elevated temperatures for some time though retaining the same overall temperature mean), in contrast, caused strong negative effects by prolonging development time (by up to 10%) and reducing body mass (-21%), especially when combined with reduced relative humidity. Detrimental effects were carried over into the adult stage, diminishing subsequent performance. Most strikingly, higher temperatures suppressed adult immune function (haemocytes: -54%, lysozyme activity: -32%), which may potentially change the way species interact with antagonists. Heat waves thus reduced fitness parameters by 10-25% for development time and body mass and by up to 54% for immune parameters even in this plastic and widespread butterfly, exemplifying the potentially dramatic impact of extreme weather events on biodiversity. © 2014. Published by The Company of Biologists Ltd.

  5. Blast-Wave Generation and Propagation in Rapidly Heated Laser-Irradiated Targets

    Science.gov (United States)

    Ivancic, S. T.; Stillman, C. R.; Nilson, P. M.; Solodov, A. A.; Froula, D. H.

    2017-10-01

    Time-resolved extreme ultraviolet (XUV) spectroscopy was used to study the creation and propagation of a >100-Mbar blast wave in a target irradiated by an intense (>1018WWcm2 cm2) laser pulse. Blast waves provide a platform to generate immense pressures in the laboratory. A temporal double flash of XUV radiation was observed when viewing the rear side of the target, which is attributed to the emergence of a blast wave following rapid heating by a fast-electron beam generated from the laser pulse. The time-history of XUV emission in the photon energy range of 50 to 200 eV was recorded with an x-ray streak camera with 7-ps temporal resolution. The heating and expansion of the target was simulated with an electron transport code coupled to 1-D radiation-hydrodynamics simulations. The temporal delay between the two flashes measured in a systematic study of target thickness and composition was found to evolve in good agreement with a Sedov-Taylor blast-wave solution. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and Department of Energy Office of Science Award Number DE-SC-0012317.

  6. [Media and public health: example of heat wave during summer 2003].

    Science.gov (United States)

    Boyer, L; Robitail, S; Debensason, D; Auquier, P; San Marco, J-L

    2005-11-01

    The summer of 2003 was the hottest for France in the last 50 years with record day and nighttime temperatures. INSERM statistics estimated that 14,802 heat-related deaths occurred during August 2003 heat wave in France. In the aftermath of this crisis, we thought that it was useful to analyze how the French media dealt with public health during the period from June 1 to August 31, 2003. The objective was to analyze French coverage of public health information during the August 2003 heat wave. Manual and computerized analysis of newspaper and radio reports published from June 1 to August 31, 2003. Articles were obtained by searching the EUROPRESS database. Text analysis was performed using the ALCESTE software package. A total of 1,599 articles were analyzed. Few articles contained warnings about heat exposure and preventive measures. Public health policy was relegated to third place after business and ecology themes. The special problems of the high-risk populations were not mentioned until after the rising death toll was known and emphasis was placed on the implications of the crisis in the political process. The findings of this study show the poor performance of public health policy in France and that media must be given guidance to fulfil its role in providing public health information. This crisis discloses the absence of public health culture in France and involves the "social exclusion" related to a breakdown of social cohesion. More cooperation is needed between the media and public health professionals to avoid future heat-wave and other public health crises. France must develop a public health culture to promote involvement of both the community and individuals in public health issues.

  7. Effects of the distribution density of a biomass combined heat and power plant network on heat utilisation efficiency in village-town systems.

    Science.gov (United States)

    Zhang, Yifei; Kang, Jian

    2017-11-01

    The building of biomass combined heat and power (CHP) plants is an effective means of developing biomass energy because they can satisfy demands for winter heating and electricity consumption. The purpose of this study was to analyse the effect of the distribution density of a biomass CHP plant network on heat utilisation efficiency in a village-town system. The distribution density is determined based on the heat transmission threshold, and the heat utilisation efficiency is determined based on the heat demand distribution, heat output efficiency, and heat transmission loss. The objective of this study was to ascertain the optimal value for the heat transmission threshold using a multi-scheme comparison based on an analysis of these factors. To this end, a model of a biomass CHP plant network was built using geographic information system tools to simulate and generate three planning schemes with different heat transmission thresholds (6, 8, and 10 km) according to the heat demand distribution. The heat utilisation efficiencies of these planning schemes were then compared by calculating the gross power, heat output efficiency, and heat transmission loss of the biomass CHP plant for each scenario. This multi-scheme comparison yielded the following results: when the heat transmission threshold was low, the distribution density of the biomass CHP plant network was high and the biomass CHP plants tended to be relatively small. In contrast, when the heat transmission threshold was high, the distribution density of the network was low and the biomass CHP plants tended to be relatively large. When the heat transmission threshold was 8 km, the distribution density of the biomass CHP plant network was optimised for efficient heat utilisation. To promote the development of renewable energy sources, a planning scheme for a biomass CHP plant network that maximises heat utilisation efficiency can be obtained using the optimal heat transmission threshold and the nonlinearity

  8. Fast wave heating and edge power losses in NSTX and NSTX-U

    Science.gov (United States)

    Bertelli, Nicola

    2013-10-01

    Experimental studies of high harmonic fast wave (HHFW) heating on the National Spherical Torus Experiment (NSTX) have demonstrated that substantial HHFW power loss can occur along the open field lines in the scrape-off layer (SOL), but the mechanism behind the loss is not yet understood. Extended ray tracing and full wave codes are being applied to specific NSTX discharges in order to predict the causes of this power loss. Previous full wave simulations predict that cavity-like modes may form outside of the LCFS. We find that inserting a collisional loss in the SOL of AORSA to represent a damping process indicates an effective collisional term of ν / ω ~ [ 0 . 05 - 0 . 1 ] which is considerably larger than the ν / ω ~ 0 . 005 obtained with Spitzer resistivity, suggesting the damping scale of the loss mechanism. The magnitude of the edge collisional losses are being used to evaluate possible potential damping mechanisms in the SOL. Initial numerical analyses show that the presence of the SOL has a significant impact on the launched antenna spectrum. The upgrade of NSTX, NSTX-U, will operate with toroidal magnetic fields (BT) up to 1 T, nearly twice the values used on NSTX. The doubling of BT while retaining the 30 MHz RF frequency moves the heating regime for NSTX-U to the mid harmonic fast wave (MHFW) regime, which will be analyzed and contrasted with the HHFW regime on NSTX. These studies indicate that direct ion damping might be more significant in NSTX-U under TRANSP predicted full performance conditions. Modifications of fast ion distributions due to the interaction of fast waves with NBI will be presented in both MHFW and HHFW regimes. Work supported by the SciDAC Center for Wave-Plasma Interactions under DE-FC02-01ER54648 and the US DOE under DE-AC02-CH0911466.

  9. Improving urban district heating systems and assessing the efficiency of the energy usage therein

    Science.gov (United States)

    Orlov, M. E.; Sharapov, V. I.

    2017-11-01

    The report describes issues in connection with improving urban district heating systems from combined heat power plants (CHPs), to propose the ways for improving the reliability and the efficiency of the energy usage (often referred to as “energy efficiency”) in such systems. The main direction of such urban district heating systems improvement suggests transition to combined heating systems that include structural elements of both centralized and decentralized systems. Such systems provide the basic part of thermal power via highly efficient methods for extracting thermal power plants turbines steam, while peak loads are covered by decentralized peak thermal power sources to be mounted at consumers’ locations, with the peak sources being also reserve thermal power sources. The methodology was developed for assessing energy efficiency of the combined district heating systems, implemented as a computer software product capable of comparatively calculating saving on reference fuel for the system.

  10. District heating and energy efficiency in detached houses of differing size and construction

    Energy Technology Data Exchange (ETDEWEB)

    Joelsson, Anna; Gustavsson, Leif [Ecotechnology, Department of Engineering, Physics and Mathematics, Mid Sweden University, SE-831 25 Oestersund (Sweden)

    2009-02-15

    House envelope measures and conversion of heating systems can reduce primary energy use and CO{sub 2} emission in the existing Swedish building stock. We analysed how the size and construction of electrically heated detached houses affect the potential for such measures and the potential for cogenerated district heating. Our starting point was two typical houses built in the 1970s. We altered the floor plans to obtain 6 houses, with heated floor space ranging between 100 and 306 m{sup 2}. One of the houses was also analysed for three energy standards with differing heat loss rates. CO{sub 2} emission, primary energy use and heating cost were estimated after implementing house envelope measures, conversions to other heating systems and changes in the generation of district heat and electricity. The study accounted for primary energy, including energy chains from natural resources to useful heat in the houses. We showed that conversion to district heating based on biomass, together with house envelope measures, reduced the primary energy use by 88% and the CO{sub 2} emission by 96%, while reducing the annual societal cost by 7%. The choice of end-use heating system was decisive for the primary energy use, with district heating being the most efficient. Neither house size nor energy standard did significantly change the ranking of the heating systems, either from a primary energy or an economic viewpoint, but did affect the extent of the annual cost reduction after implementing the measures. (author)

  11. Reconsideration of Criteria and Modeling in Order to Optimize the Efficiency of Irreversible Thermomechanical Heat Engines

    Directory of Open Access Journals (Sweden)

    Michel Feidt

    2010-12-01

    Full Text Available The purpose of this work is to precise and complete one recently proposed in the literature and relative to a general criterion to maximize the first law efficiency of irreversible heat engines. It is shown that the previous proposal seems to be a particular case. A new proposal has been developed for a Carnot irreversible thermomechanical heat engine at steady state associated to two infinite heat reservoirs (hot source, and cold sink: this constitutes the studied system. The presence of heat leak is accounted for, with the most simple form, as is done generally in the literature. Irreversibility is modeled through , created internal entropy rate in the converter (engine, and , total created entropy rate in the system. Heat transfer laws are represented as general functions of temperatures. These concepts are particularized to the most common heat transfer law (linear one. Consequences of the proposal are examined; some new analytical results are proposed for efficiencies.

  12. The temporal behaviour of MHD waves in a partially ionized prominence-like plasma: Effect of heating and cooling

    Science.gov (United States)

    Ballester, J. L.; Carbonell, M.; Soler, R.; Terradas, J.

    2018-01-01

    Context. During heating or cooling processes in prominences, the plasma microscopic parameters are modified due to the change of temperature and ionization degree. Furthermore, if waves are excited on this non-stationary plasma, the changing physical conditions of the plasma also affect wave dynamics. Aims: Our aim is to study how temporal variation of temperature and microscopic plasma parameters modify the behaviour of magnetohydrodynamic (MHD) waves excited in a prominence-like hydrogen plasma. Methods: Assuming optically thin radiation, a constant external heating, the full expression of specific internal energy, and a suitable energy equation, we have derived the profiles for the temporal variation of the background temperature. We have computed the variation of the ionization degree using a Saha equation, and have linearized the single-fluid MHD equations to study the temporal behaviour of MHD waves. Results: For all the MHD waves considered, the period and damping time become time dependent. In the case of Alfvén waves, the cut-off wavenumbers also become time dependent and the attenuation rate is completely different in a cooling or heating process. In the case of slow waves, while it is difficult to distinguish the slow wave properties in a cooling partially ionized plasma from those in an almost fully ionized plasma, the period and damping time of these waves in both plasmas are completely different when the plasma is heated. The temporal behaviour of the Alfvén and fast wave is very similar in the cooling case, but in the heating case, an important difference appears that is related with the time damping. Conclusions: Our results point out important differences in the behaviour of MHD waves when the plasma is heated or cooled, and show that a correct interpretation of the observed prominence oscillations is very important in order to put accurate constraints on the physical situation of the prominence plasma under study, that is, to perform prominence

  13. Thermal Efficiency of Power Module “Boiler with Solar Collectors as Additional Heat Source” For Combined Heat Supply System

    Directory of Open Access Journals (Sweden)

    Denysova A.E.

    2015-04-01

    Full Text Available The purpose of work is to increase the efficiency of the combined heat supply system with solar collectors as additional thermal generators. In order to optimize the parameters of combined heat supply system the mathematical modeling of thermal processes in multi module solar collectors as additional thermal generators for preheating of the water for boiler have been done. The method of calculation of multi-module solar collectors working with forced circulation for various configurations of hydraulic connection of solar collector modules as the new result of our work have been proposed. The results of numerical simulation of thermal efficiency of solar heat source for boiler of combined heat supply system with the account of design features of the circuit; regime parameters of thermal generators that allow establishing rational conditions of its functioning have been worked out. The conditions of functioning that provide required temperature of heat carrier incoming to boiler and value of flow rate at which the slippage of heat carrier is not possible for different hydraulic circuits of solar modules have been established.

  14. Quantifying Systemic Efficiency using Exergy and Energy Analysis for Ground Source Heat Pumps: Domestic Space Conditioning and Water Heating Applications.

    Energy Technology Data Exchange (ETDEWEB)

    Ally, Moonis Raza [ORNL; Baxter, Van D [ORNL; Gehl, Anthony C [ORNL; Munk, Jeffrey D [ORNL

    2017-01-01

    Although air temperatures over land surfaces show wide seasonal and daily variations, the ground, approximately 10 meters below the earth s surface, remains relatively stable in temperature thereby serving as an energy source or sink. Ground source heat pumps can heat, cool, and supply homes with hot water efficiently by utilizing the earth s renewable and essentially inexhaustible energy resources, saving fossil fuels, reducing greenhouse gas emissions, and lowering the environmental footprint. In this paper, evidence is shown that ground source heat pumps can provide up to 79%-87% of domestic hot water energy needs, and up to 77% of space heating needs with the ground s thermal energy resources. The case refers to a 12-month study conducted at a 253 m2 research house located in Oak Ridge, Tennessee, 36.01 N 84.26 W in a mixed-humid climate with HDD of 2218 C-days and CDD of 723 C-days under simulated occupancy conditions. A single 94.5m vertical bore interfaced the heat pump with the ground. The research shows that this technology is capable of achieving US DOE targets of 25 % and 35% energy savings in HVAC, and in water heating, respectively by 2030. It is also a viable technology to meet greenhouse gas target emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources. The paper quantifies systemic efficiencies using Exergy analysis of the major components, clearly pointing areas for further improvement.

  15. A Compact, Light-weight, Reliable and Highly Efficient Heat Pump for Project

    Data.gov (United States)

    National Aeronautics and Space Administration — RTI proposes to develop an efficient, reliable, compact and lightweight heat pump for space applications. The proposed effort is expected to lead to (at the end of...

  16. Heat-Flux Measurements in Laser-Produced Plasmas Using Thomson Scattering from Electron Plasma Waves

    Science.gov (United States)

    Henchen, R. J.; Goncharov, V. N.; Cao, D.; Katz, J.; Froula, D. H.; Rozmus, W.

    2017-10-01

    An experiment was designed to measure heat flux in coronal plasmas using collective Thomson scattering. Adjustments to the electron distribution function resulting from heat flux affect the shape of the collective Thomson scattering features through wave-particle resonance. The amplitude of the Spitzer-Härm electron distribution function correction term (f1) was varied to match the data and determines the value of the heat flux. Independent measurements of temperature and density obtained from Thomson scattering were used to infer the classical heat flux (q = - κ∇Te) . Time-resolved Thomson-scattering data were obtained at five locations in the corona along the target normal in a blowoff plasma formed from a planar Al target with 1.5 kJ of 351-nm laser light in a 2-ns square pulse. The flux measured through the Thomson-scattering spectra is a factor of 5 less than the κ∇Te measurements. The lack of collisions of heat-carrying electrons suggests a nonlocal model is needed to accurately describe the heat flux. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  17. The study of the mobile compressor unit heat losses recovery system waste heat exchanger thermal insulation types influence on the operational efficiency

    Science.gov (United States)

    Yusha, V. L.; Chernov, G. I.; Kalashnikov, A. M.

    2017-08-01

    The paper examines the mobile compressor unit (MCU) heat losses recovery system waste heat exchanger prototype external thermal insulation types influence on the operational efficiency. The study is conducted by means of the numerical method through the modellingof the heat exchange processes carried out in the waste heat exchanger in ANSUS. Thermaflex, mineral wool, penofol, water and air were applied as the heat exchanger external insulation. The study results showed the waste heat exchanger external thermal insulationexistence or absence to have a significant impact on the heat exchanger operational efficiency.

  18. X-ray analysis of electron Bernstein wave heating in MST

    Science.gov (United States)

    Seltzman, A. H.; Anderson, J. K.; DuBois, A. M.; Almagri, A.; Forest, C. B.

    2016-11-01

    A pulse height analyzing x-ray tomography system has been developed to detect x-rays from electron Bernstein wave heated electrons in the Madison symmetric torus reversed field pinch (RFP). Cadmium zinc telluride detectors are arranged in a parallel beam array with two orthogonal multi-chord detectors that may be used for tomography. In addition a repositionable 16 channel fan beam camera with a 55° field of view is used to augment data collected with the Hard X-ray array. The chord integrated signals identify target emission from RF heated electrons striking a limiter located 12° toroidally away from the RF injection port. This provides information on heated electron spectrum, transport, and diffusion. RF induced x-ray emission from absorption on harmonic electron cyclotron resonances in low current (<250 kA) RFP discharges has been observed.

  19. X-ray analysis of electron Bernstein wave heating in MST

    Energy Technology Data Exchange (ETDEWEB)

    Seltzman, A. H., E-mail: seltzman@wisc.edu; Anderson, J. K.; DuBois, A. M.; Almagri, A.; Forest, C. B. [Department of Physics, University of Wisconsin, Madison, Wisconsin 53706 (United States)

    2016-11-15

    A pulse height analyzing x-ray tomography system has been developed to detect x-rays from electron Bernstein wave heated electrons in the Madison symmetric torus reversed field pinch (RFP). Cadmium zinc telluride detectors are arranged in a parallel beam array with two orthogonal multi-chord detectors that may be used for tomography. In addition a repositionable 16 channel fan beam camera with a 55° field of view is used to augment data collected with the Hard X-ray array. The chord integrated signals identify target emission from RF heated electrons striking a limiter located 12° toroidally away from the RF injection port. This provides information on heated electron spectrum, transport, and diffusion. RF induced x-ray emission from absorption on harmonic electron cyclotron resonances in low current (<250 kA) RFP discharges has been observed.

  20. Recovery Act: Tennessee Energy Efficient Schools Initiative Ground Source Heat Pump Program

    Energy Technology Data Exchange (ETDEWEB)

    Townsend, Terry [Townsend Engineering, Inc., Davenport, IA (United States); Slusher, Scott [Townsend Engineering, Inc., Davenport, IA (United States)

    2017-04-24

    The Tennessee Energy Efficient Schools Initiative (EESI) Hybrid-Water Source Heat Pump (HY-GSHP) Program sought to provide installation costs and operation costs for different Hybrid water source heat pump systems’ configurations so that other State of Tennessee School Districts will have a resource for comparison purposes if considering a geothermal system.

  1. Analysis of the Thermodynamical Efficiency of an Air Handling Unit with a Heat Pump

    Directory of Open Access Journals (Sweden)

    Vytautas Martinaitis

    2012-12-01

    Full Text Available This paper evaluates the seasonal thermodynamic efficiency of the air-to-air heat pump used for a heat recovery ventilation system and several modulations of compressors affecting the thermodynamic efficiency of the heat pump. A variable speed and on/off-type compressors have been selected. In order to evaluate the thermodynamic potential of the device, energy analysis has been performed. Along with modelling the operation of the air handling unit during the cold time of the year, variations in the thermodynamic efficiency or different modulation compressors have been compared. The obtained results have shown that the use of a few simple compressors causes a decrease in the seasonal parameters of the heat pump: heat generated by a condenser is 5% lower compared to the use of variable speed compressors and therefore the seasonal coefficient of the performance (COP of the heat pump decreases by 5%. Possible improvement on the heat pump can be provided changing the compressor into variable speed or modulatory equipment, which allows adjusting to heat demand and thus increases the seasonal efficiency of the system from a thermodynamic point of view.Article in Lithuanian

  2. Long-duration heat load measurement approach by novel apparatus design and highly efficient algorithm

    Science.gov (United States)

    Zhu, Yanwei; Yi, Fajun; Meng, Songhe; Zhuo, Lijun; Pan, Weizhen

    2017-11-01

    Improving the surface heat load measurement technique for vehicles in aerodynamic heating environments is imperative, regarding aspects of both the apparatus design and identification efficiency. A simple novel apparatus is designed for heat load identification, taking into account the lessons learned from several aerodynamic heating measurement devices. An inverse finite difference scheme (invFDM) for the apparatus is studied to identify its surface heat flux from the interior temperature measurements with high efficiency. A weighted piecewise regression filter is also proposed for temperature measurement prefiltering. Preliminary verification of the invFDM scheme and the filter is accomplished via numerical simulation experiments. Three specific pieces of apparatus have been concretely designed and fabricated using different sensing materials. The aerodynamic heating process is simulated by an inductively coupled plasma wind tunnel facility. The identification of surface temperature and heat flux from the temperature measurements is performed by invFDM. The results validate the high efficiency, reliability and feasibility of heat load measurements with different heat flux levels utilizing the designed apparatus and proposed method.

  3. Comparative Calculation of Heat Exchange with the Ground in Residential Building Including Periodes of Heat Waves

    Directory of Open Access Journals (Sweden)

    Staszczuk Anna

    2016-06-01

    Full Text Available The paper provides verification of 3D transient ground-coupled model to calculation of heat exchange between ground and typical one-storey, passive residential building. The model was performed with computer software WUFI®plus and carried out to estimate the indoor air temperatures during extending hot weather periods. For verifying the results of calculations performed by the WUFI®plus software, the most recent version of EnergyPlus software version was used. Comparison analysis of calculation results obtained with the two above mentioned calculation method was made for two scenarios of slab on ground constructions: without thermal insulation and with thermal insulation under the whole slab area. Comprehensive statistical analysis was done including time series analysis and descriptive statistics parameters.

  4. The Relation between Temperature, Ozone, and Mortality in Nine French Cities during the Heat Wave of 2003

    National Research Council Canada - National Science Library

    Laurent Filleul; Sylvie Cassadou; Sylvia Médina; Pascal Fabres; Agnés Lefranc; Daniel Eilstein; Alain Le Tertre; Laurence Pascal; Benoit Chardon; Myriam Blanchard; Christophe Declercq; Jean-François Jusot; Hélène Prouvost; Martine Ledrans

    2006-01-01

    .... During this period, elevated ozone concentrations were measured all over the country. Questions were raised concerning the contribution of O to the health impact of the summer 2003 heat wave. Methods...

  5. Improving Geothermal Heat Pump Air Conditioning Efficiency with Wintertime Cooling using Seasonal Thermal Energy Storage (STES). Application Manual

    Science.gov (United States)

    2016-11-01

    APPLICATION MANUAL Improving Geothermal Heat Pump Air Conditioning Efficiency with Wintertime Cooling using Seasonal Thermal Energy Storage...application projects to increase energy efficiency and occupant comfort. Seasonal Thermal Energy Storage (STES) technology, energy efficiency, geothermal heat...electrical energy use (kW-hr) for the geothermal heat pump system with and without a dry fluid cooler

  6. Developing HEAT Scores with H-Res Thermal Imagery to Support Urban Energy Efficiency

    Science.gov (United States)

    Hemachandran, Bharanidharan

    As part of The Calgary Community GHG Reduction Plan (2009) The City is seeking an implementation strategy to reduce GHGs and promote low-carbon living, with a focus on improving urban energy efficiency. The most cited obstacle to energy efficiency improvements is the lack of interest from consumers (CUI, 2008). However, Darby (2006) has shown that effective feedback significantly reduces energy consumption. To exploit these findings, the HEAT (Heat Energy Assessment Technologies) Geoweb project integrates high-resolution (H-Res) airborne thermal imagery (TABI 1800) to provide unique energy efficiency feedback to Calgary homeowners in the form of interactive HEAT Maps and Hot Spots (Hay et al., 2011). As a part of the HEAT Phase II program, the goal of this research is to provide enhanced feedback support for urban energy efficiency by meeting two key objectives: (i) develop an appropriate method to define HEAT Scores using TABI 1800 imagery that allows for the comparison of waste heat of one or more houses with all other mapped houses in the community and city, and (ii) develop a multi-scale interactive Geoweb interface that displays the HEAT Scores at City, Community and Residential scales. To achieve these goals, we describe the evolution of three novel HEAT Score techniques based on: (i) a Standardized Score, (ii) the WUFIRTM model and Logistic Regression and (iii ) a novel criteria weighted method that considers: (a) heat transfer through different roofing materials, (b) local climatic conditions and (c) house age and living area attributes. Furthermore, (d) removing or adding houses to analysis based on this 3rd technique, does not affect the HEAT Score of other houses and (e) HEAT Scores can be compared within and across different cities. We also describe how HEAT Scores are incorporated within the HEAT Geoweb architecture. It is envisioned that HEAT Scores will promote energy efficiency among homeowners and urban city planners, as they will quantify and

  7. An efficient algorithm for computation of solitary wave solutions to nonlinear differential equations

    Science.gov (United States)

    Ayub, Kamran; Khan, M. Yaqub; Mahmood-Ul-Hassan, Qazi; Ahmad, Jamshad

    2017-09-01

    Nonlinear mathematical problems and their solutions attain much attention in solitary waves. In soliton theory, an efficient tool to attain various types of soliton solutions is the \\exp (-φ (ζ ))-expansion technique. This article is devoted to find exact travelling wave solutions of Drinfeld-Sokolov equation via a reliable mathematical technique. By using the proposed technique, we attain soliton wave solution of various types. It is observed that the technique under discussion is user friendly with minimum computational work, and can be extended for physical problems of different nature in mathematical physics.

  8. An efficient domain decomposition strategy for wave loads on surface piercing circular cylinders

    DEFF Research Database (Denmark)

    Paulsen, Bo Terp; Bredmose, Henrik; Bingham, Harry B.

    2014-01-01

    A fully nonlinear domain decomposed solver is proposed for efficient computations of wave loads on surface piercing structures in the time domain. A fully nonlinear potential flow solver was combined with a fully nonlinear Navier–Stokes/VOF solver via generalized coupling zones of arbitrary shape....... Sensitivity tests of the extent of the inner Navier–Stokes/VOF domain were carried out. Numerical computations of wave loads on surface piercing circular cylinders at intermediate water depths are presented. Four different test cases of increasing complexity were considered; 1) weakly nonlinear regular waves...

  9. Evaluating humidity recovery efficiency of currently available heat and moisture exchangers: a respiratory system model study.

    Science.gov (United States)

    Lucato, Jeanette Janaina Jaber; Adams, Alexander Bernard; Souza, Rogério; Torquato, Jamili Anbar; Carvalho, Carlos Roberto Ribeiro; Marini, John J

    2009-01-01

    To evaluate and compare the efficiency of humidification in available heat and moisture exchanger models under conditions of varying tidal volume, respiratory rate, and flow rate. Inspired gases are routinely preconditioned by heat and moisture exchangers to provide a heat and water content similar to that provided normally by the nose and upper airways. The absolute humidity of air retrieved from and returned to the ventilated patient is an important measurable outcome of the heat and moisture exchangers' humidifying performance. Eight different heat and moisture exchangers were studied using a respiratory system analog. The system included a heated chamber (acrylic glass, maintained at 37 degrees C), a preserved swine lung, a hygrometer, circuitry and a ventilator. Humidity and temperature levels were measured using eight distinct interposed heat and moisture exchangers given different tidal volumes, respiratory frequencies and flow-rate conditions. Recovery of absolute humidity (%RAH) was calculated for each setting. Increasing tidal volumes led to a reduction in %RAH for all heat and moisture exchangers while no significant effect was demonstrated in the context of varying respiratory rate or inspiratory flow. Our data indicate that heat and moisture exchangers are more efficient when used with low tidal volume ventilation. The roles of flow and respiratory rate were of lesser importance, suggesting that their adjustment has a less significant effect on the performance of heat and moisture exchangers.

  10. IR Hot Wave

    Energy Technology Data Exchange (ETDEWEB)

    Graham, T. B.

    2010-04-01

    The IR Hot Wave{trademark} furnace is a breakthrough heat treatment system for manufacturing metal components. Near-infrared (IR) radiant energy combines with IR convective heating for heat treating. Heat treatment is an essential process in the manufacture of most components. The controlled heating and cooling of a metal or metal alloy alters its physical, mechanical, and sometimes chemical properties without changing the object's shape. The IR Hot Wave{trademark} furnace offers the simplest, quickest, most efficient, and cost-effective heat treatment option for metals and metal alloys. Compared with other heat treatment alternatives, the IR Hot Wave{trademark} system: (1) is 3 to 15 times faster; (2) is 2 to 3 times more energy efficient; (3) is 20% to 50% more cost-effective; (4) has a {+-}1 C thermal profile compared to a {+-}10 C thermal profile for conventional gas furnaces; and (5) has a 25% to 50% smaller footprint.

  11. Meteorological factors influencing characteristics of heat waves and cold spells over Central Europe in EURO-CORDEX RCMs

    Science.gov (United States)

    Plavcova, Eva; Kysely, Jan

    2017-04-01

    We evaluate the ability of current regional climate models (RCMs) to simulate temporal characteristics of heat waves and cold spells over Central Europe. We compare EURO-CORDEX RCMs driven by both global climate models and the ERA-INTERIM reanalysis against observations over the reference period 1980-2005. We focus on heat waves in summer and cold spells in winter over Central Europe (48.5-51.5 N and 12-18 E). We find that some RCMs have difficulties to reproduce basic characteristics of heat waves and cold spells (such as frequency and duration). Most RCMs overestimate length of the longest heat waves and cold spells. We detected that models have a stronger tendency to cluster days of heat waves and cold spells in individual years compared to observations, which results in more extreme seasons in RCMs. We analyze climatological characteristics and meteorological factors related to the persistence of heat waves and cold spells, with focus on simulated atmospheric circulation and precipitation deficits.

  12. Thermal Efficiency of Cogeneration Units with Multi-Stage Reheating for Russian Municipal Heating Systems

    Directory of Open Access Journals (Sweden)

    Evgeny Lisin

    2016-04-01

    Full Text Available This paper explores the layout of an optimum process for supplying heat to Russian municipal heating systems operating in a market environment. We analyze and compare the standard cogeneration unit design with two-stage reheating of service water coming from controlled extraction locations and layouts that employ three in-line reheaters with heat the supply controlled by a rotary diaphragm and qualitative/quantitative methods (so-called “uncontrolled extraction”. Cogeneration unit designs are benchmarked in terms of their thermal efficiency expressed as a fuel consumption rate. The specific fuel consumption rate on electricity production is viewed as a key parameter of thermal efficiency.

  13. Biomimic design of multi-scale fabric with efficient heat transfer property

    Directory of Open Access Journals (Sweden)

    Fan Jie

    2012-01-01

    Full Text Available Wool fiber has a complex hierarchic structure. The multi-scale fibrils are assembled to form a tree-like channel net in wool fiber, providing an efficient heat transfer property. The optimal inner configuration of wool fiber can also be invited to biomimic design of textile fabrics to improve the thermal comfort of cloth. A heat transfer model of biomimic multi-scale fabric using the fractal derivative is established. Theoretical analysis indicates that the heat flux efficiency in the biomimic fabric can be 2 orders of magnitude comparing with that of the continuous medium.

  14. An efficient flexible-order model for coastal and ocean water waves

    DEFF Research Database (Denmark)

    Engsig-Karup, Allan Peter; Bingham, Harry B.; Lindberg, Ole

    Current work are directed toward the development of an improved numerical 3D model for fully nonlinear potential water waves over arbitrary depths. The model is high-order accurate, robust and efficient for large-scale problems, and support will be included for flexibility in the description...... of structures. The mathemathical equations for potential waves in the physical domain is transformed through $\\sigma$-mapping(s) to a time-invariant boundary-fitted domain which then becomes a basis for an efficient solution strategy. The improved 3D numerical model is based on a finite difference method...

  15. Calculation of Efficiencies of a Ship Power Plant Operating with Waste Heat Recovery through Combined Heat and Power Production

    Directory of Open Access Journals (Sweden)

    Mirko Grljušić

    2015-05-01

    Full Text Available The aim of this research was to investigate the possibility of a combined heat & power (CHP plant, using the waste heat from a Suezmax-size oil tanker’s main engine, to meet all heating and electricity requirements during navigation. After considering various configurations, a standard propulsion engine operating at maximum efficiency, combined with a supercritical Organic Rankine cycle (ORC system, was selected to supply the auxiliary power, using R245fa or R123 as the working fluid. The system analysis showed that such a plant can meet all heat and electrical power requirements at full load, with the need to burn only a small amount of supplementary fuel in a heat recovery steam generator (HRSG when the main engine operates at part load. Therefore, it is possible to increase the overall thermal efficiency of the ship’s power plant by more than 5% when the main engine operates at 65% or more of its specified maximum continuous rating (SMCR.

  16. ECOHEATCOOL Work Package 4. Guidelines for assessing the efficiency of district heating and district cooling system

    Energy Technology Data Exchange (ETDEWEB)

    Werner, Sven [Chalmers Univ. of Technology, Goeteborg (Sweden)] (and others)

    2006-07-01

    higher than the current total net heat demand for the industrial, residential, and service sectors in the target area. The highest potential appears for geothermal heat, but the available heat resources from CHP and biomass are also significant. Hence, no limitations appear with respect to available strategic fuel and heat sources for more district heating in Europe. Major barriers for district heating have during recent years been low fuel and electricity prices, focus on short term investments, existing legal frameworks, energy supply focus, ownership shifts, price regulation, distorted market prices, cost allocation methods, social obligations, and the introductory rules in the new European emissions trading system. The total net heat demand for the industrial, residential, and service sectors has been estimated to 20,8 EJ/year. The additional possible potential for district heat sales has been estimated to 6,8 EJ/year, which is 3,4 times higher than the current district heat sales of 2,0 EJ/year. Hence, no limitations appear with respect to available heat demands for expansion of the European district heating systems. The overall benefits with district heating were identified as higher energy efficiency, higher security of supply, and lower carbon dioxide emissions. The overall benefits have been estimated for three cases: The current (2003) situation, Improved heat generation at current heat sales, and Doubling heat sales with the improved composition of heat generation. In the case of doubling the heat sales, higher energy efficiency would be registered as the primary energy supply can be reduced with 2,14 EJ/year, corresponding to the whole energy balance of Sweden. The higher security of supply for the same case became a reduction of the import dependency with 4,45 EJ/year, corresponding to 5,5 % of all primary energy supply or more than the whole energy balance of Poland. The reduction of carbon dioxide emissions from the first to the third case was estimated to

  17. High Efficiency Heat Exchanger for High Temperature and High Pressure Applications

    Energy Technology Data Exchange (ETDEWEB)

    Sienicki, James J. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Lv, Qiuping [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Moisseytsev, Anton [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

    2017-09-29

    CompRex, LLC (CompRex) specializes in the design and manufacture of compact heat exchangers and heat exchange reactors for high temperature and high pressure applications. CompRex’s proprietary compact technology not only increases heat exchange efficiency by at least 25 % but also reduces footprint by at least a factor of ten compared to traditional shell-and-tube solutions of the same capacity and by 15 to 20 % compared to other currently available Printed Circuit Heat Exchanger (PCHE) solutions. As a result, CompRex’s solution is especially suitable for Brayton cycle supercritical carbon dioxide (sCO2) systems given its high efficiency and significantly lower capital and operating expenses. CompRex has already successfully demonstrated its technology and ability to deliver with a pilot-scale compact heat exchanger that was under contract by the Naval Nuclear Laboratory for sCO2 power cycle development. The performance tested unit met or exceeded the thermal and hydraulic specifications with measured heat transfer between 95 to 98 % of maximum heat transfer and temperature and pressure drop values all consistent with the modeled values. CompRex’s vision is to commercialize its compact technology and become the leading provider for compact heat exchangers and heat exchange reactors for various applications including Brayton cycle sCO2 systems. One of the limitations of the sCO2 Brayton power cycle is the design and manufacturing of efficient heat exchangers at extreme operating conditions. Current diffusion-bonded heat exchangers have limitations on the channel size through which the fluid travels, resulting in excessive solid material per heat exchanger volume. CompRex’s design allows for more open area and shorter fluid proximity for increased heat transfer efficiency while sustaining the structural integrity needed for the application. CompRex is developing a novel improvement to its current heat exchanger design where fluids are directed to alternating

  18. Development of a Wind Directly Forced Heat Pump and Its Efficiency Analysis

    Directory of Open Access Journals (Sweden)

    Ching-Song Jwo

    2013-01-01

    Full Text Available The requirements of providing electric energy through the wind-forced generator to the heat pump for water cooling and hot water heating grow significantly by now. This study proposes a new technique to directly adopt the wind force to drive heat pump systems, which can effectively reduce the energy conversion losses during the processes of wind force energy converting to electric energy and electric energy converting to kinetic energy. The operation of heat pump system transfers between chiller and heat that are controlled by a four-way valve. The theoretical efficiency of the traditional method, whose heat pump is directly forced by wind, is 42.19%. The experimental results indicated average value for cool water producing efficiency of 54.38% in the outdoor temperature of 35°C and the indoor temperature of 25°C and the hot water producing efficiency of 52.25% in the outdoor temperature and the indoor temperature both of 10°C. We proposed a method which can improve the efficiency over 10% in both cooling and heating.

  19. Advanced Thermoelectric Materials for Efficient Waste Heat Recovery in Process Industries

    Energy Technology Data Exchange (ETDEWEB)

    Adam Polcyn; Moe Khaleel

    2009-01-06

    The overall objective of the project was to integrate advanced thermoelectric materials into a power generation device that could convert waste heat from an industrial process to electricity with an efficiency approaching 20%. Advanced thermoelectric materials were developed with figure-of-merit ZT of 1.5 at 275 degrees C. These materials were not successfully integrated into a power generation device. However, waste heat recovery was demonstrated from an industrial process (the combustion exhaust gas stream of an oxyfuel-fired flat glass melting furnace) using a commercially available (5% efficiency) thermoelectric generator coupled to a heat pipe. It was concluded that significant improvements both in thermoelectric material figure-of-merit and in cost-effective methods for capturing heat would be required to make thermoelectric waste heat recovery viable for widespread industrial application.

  20. Thermophysical Analysis of the Efficiency of Regulating Heat Consumption of a Building

    Science.gov (United States)

    Krukovskii, P. G.; Tadlya, O. Yu.; Daineko, A. I.; Sklyarenko, D. I.

    2017-09-01

    Analysis has been made of the methods of improving the energy consumption efficiency of buildings by controlling the heat consumption by various devices (including individual heat points) without and with account for the air temperature control in a room (presence of feedback). Particular consideration was given to the low-cost method of energy saving by decreasing the air temperature in the absence of people, which at present is used inadequately, although its potential can reach 15-20%. The investigations carried out by us have shown that to effectively regulate the energy consumption with the aim of its saving, it is necessary to introduce feedback between the rooms of the building and the individual heat points. Analysis of the thermal state of an old office building with a low energy-efficiency has enabled us to develop methods for decreasing energy consumption by up to 4% for district heating and up to 10% for individual heating.

  1. Plasma Heating During the Parametric Excitation of Acoustic Waves in Coronal Magnetic Loops

    Science.gov (United States)

    Zaitsev, V. V.; Kislyakova, K. G.

    When studying microwave emission of active regions on the Sun, an effect of parametric resonance between 5-min velocity oscillations in the solar photosphere and sound oscillations of coronal magnetic loops modulating the microwave emission has been discovered for the first time. The effect shows itself as simultaneous excitation in coronal magnetic loop oscillations with periods 5, 10, and 3 min, which correspond to the pumping frequency, subharmonic, and the first upper frequency of parametric resonance. The parametric resonance can serve as an effective channel of transporting the energy of photospheric oscillations into the upper layers of the solar atmosphere. The energy of acoustic waves excited in a coronal magnetic loop, rate of dissipation of acoustic waves, and rate of heating of the coronal plasma are determined. The maximum temperature predicted for the apex of the loop is calculated as a function of velocity of photospheric oscillations, length of the loop, and electric current in the loop. It is shown that the mechanism proposed can explain the origin of quasi-stationary X-ray loops with temperatures of 3-6 MK. The lengths of these loops are resonant for acoustic waves excited by the 5-min photospheric oscillations. The use of the proposed mechanism to explain heating of the X-ray loops expected to be on stars of late spectral types is discussed.

  2. Control of wave-driven turbulence and surface heating on the mixing of microplastic marine debris

    Science.gov (United States)

    Kukulka, T.; Lavender Law, K. L.; Proskurowski, G. K.

    2016-02-01

    Buoyant microplastic marine debris (MPMD) is a pollutant in the ocean surface boundary layer (OSBL) that is submerged by turbulent transport processes. Langmuir circulation (LC) is a turbulent process driven by wind and surface waves that enhances mixing in the OSBL. Sea surface cooling also contributes to OSBL turbulence by driving convection. On the other hand, sea surface heating stratifies and stabilizes the water column to reduce turbulent motion. We analyze observed MPMD surface concentrations in the Atlantic and Pacific Oceans to reveal a significant increase in MPMD concentrations during surface heating and a decrease during surface cooling. Turbulence resolving large eddy simulations of the OSBL for an idealized diurnal heating cycle suggest that turbulent downward fluxes of buoyant tracers are enhanced at night, facilitating deep submergence of plastics, and suppressed in heating conditions, resulting in surface trapped MPMD. Simulations agree with observations if enhanced mixing due to LC is included. Our results demonstrate the controlling influence of surface heat fluxes and LC on turbulent transport in the OSBL and on vertical distributions of buoyant marine particles.

  3. Investigation of impurity confinement in lower hybrid wave heated plasma on EAST tokamak

    Science.gov (United States)

    Xu, Z.; Wu, Z. W.; Zhang, L.; Gao, W.; Ye, Y.; Chen, K. Y.; Yuan, Y.; Zhang, W.; Yang, X. D.; Chen, Y. J.; Zhang, P. F.; Huang, J.; Wu, C. R.; Morita, S.; Oishi, T.; Zhang, J. Z.; Duan, Y. M.; Zang, Q.; Ding, S. Y.; Liu, H. Q.; Chen, J. L.; Hu, L. Q.; Xu, G. S.; Guo, H. Y.; the EAST team

    2018-01-01

    The transient perturbation method with metallic impurities such as iron (Fe, Z  =  26) and copper (Cu, Z  =  29) induced in plasma-material interaction (PMI) procedure is used to investigate the impurity confinement characters in lower hybrid wave (LHW) heated EAST sawtooth-free plasma. The dependence of metallic impurities confinement time on plasma parameters (e.g. plasma current, toroidal magnetic field, electron density and heating power) are investigated in ohmic and LHW heated plasma. It is shown that LHW heating plays an important role in the reduction of the impurity confinement time in L-mode discharges on EAST. The impurity confinement time scaling is given as 42IP0.32Bt0.2\\overline{n}e0.43Ptotal-0.4~ on EAST, which is close to the observed scaling on Tore Supra and JET. Furthermore, the LHW heated high-enhanced-recycling (HER) H-mode discharges with ~25 kHz edge coherent modes (ECM), which have lower impurity confinement time and higher energy confinement time, provide promising candidates for high performance and steady state operation on EAST.

  4. Efficiencies and coefficients of performance of heat engines, refrigerators, and heat pumps with friction: a universal limiting behavior.

    Science.gov (United States)

    Bizarro, João P S; Rodrigues, Paulo

    2012-11-01

    For work-producing heat engines, or work-consuming refrigerators and heat pumps, the percentage decrease caused by friction in their efficiencies, or coefficients of performance (COP's), is approximately given by the ratio W(fric)/W between the work spent against friction forces and the work performed by, or delivered to, the working fluid. This universal scaling, which applies in the limit of small friction (W(fric)/W friction losses can have on the FOM's of thermal engines and plants, or of the level of those losses from the observed and predicted FOM's. In the case of refrigerators and heat pumps, if W(fric)/W friction approaches asymptotically (W(fric)/W)/(1+W(fric)/W) instead of W(fric)/W. Estimates for the level of frictional losses using the Carnot (or, for heat engines and power plants only, the Curzon-Ahlborn) predictions and observed FOM's of real power plants, heat engines, refrigerators, and heat pumps show that they usually operate in domains where these behaviors are valid.

  5. Definition of temperature thresholds: the example of the French heat wave warning system

    Science.gov (United States)

    Pascal, Mathilde; Wagner, Vérène; Le Tertre, Alain; Laaidi, Karine; Honoré, Cyrille; Bénichou, Françoise; Beaudeau, Pascal

    2013-01-01

    Heat-related deaths should be somewhat preventable. In France, some prevention measures are activated when minimum and maximum temperatures averaged over three days reach city-specific thresholds. The current thresholds were computed based on a descriptive analysis of past heat waves and on local expert judgement. We tested whether a different method would confirm these thresholds. The study was set in the six cities of Paris, Lyon, Marseille, Nantes, Strasbourg and Limoges between 1973 and 2003. For each city, we estimated the excess in mortality associated with different temperature thresholds, using a generalised additive model, controlling for long-time trends, seasons and days of the week. These models were used to compute the mortality predicted by different percentiles of temperatures. The thresholds were chosen as the percentiles associated with a significant excess mortality. In all cities, there was a good correlation between current thresholds and the thresholds derived from the models, with 0°C to 3°C differences for averaged maximum temperatures. Both set of thresholds were able to anticipate the main periods of excess mortality during the summers of 1973 to 2003. A simple method relying on descriptive analysis and expert judgement is sufficient to define protective temperature thresholds and to prevent heat wave mortality. As temperatures are increasing along with the climate change and adaptation is ongoing, more research is required to understand if and when thresholds should be modified.

  6. Drought and Heat Waves: The Role of SST and Land Surface Feedbacks

    Science.gov (United States)

    Schubert, Siegfried

    2011-01-01

    Drought occurs on a wide range of time scales, and within a variety of different types of regional climates. At the shortest time scales it is often associated with heat waves that last only several weeks to a few months but nevertheless can have profound detrimental impacts on society (e.g., heat-related impacts on human health, desiccation of croplands, increased fire hazard), while at the longest time scales it can extend over decades and can lead to long term structural changes in many aspects of society (e.g., agriculture, water resources, wetlands, tourism, population shifts). There is now considerable evidence that sea surface temperatures (SSTs) play a leading role in the development of drought world-wide, especially at seasonal and longer time scales, though land-atmosphere feedbacks can also play an important role. At shorter (subseasonal) time scales, SSTs are less important, but land feedbacks can play a critical role in maintaining and amplifying the atmospheric conditions associated with heat waves and short-term droughts. This talk reviews our current understanding of the physical mechanisms that drive precipitation and temperature variations on subseasonal to centennial time scales. This includes an assessment of predictability, prediction skill, and user needs at all time scales.

  7. Efficiency Analysis of Independent and Centralized Heating Systems for Residential Buildings in Northern Italy

    Directory of Open Access Journals (Sweden)

    Fabio Rinaldi

    2011-11-01

    Full Text Available The primary energy consumption in residential buildings is determined by the envelope thermal characteristics, air change, outside climatic data, users’ behaviour and the adopted heating system and its control. The new Italian regulations strongly suggest the installation of centralized boilers in renovated buildings with more than four apartments. This work aims to investigate the differences in primary energy consumption and efficiency among several independent and centralized heating systems installed in Northern Italy. The analysis is carried out through the following approach: firstly building heating loads are evaluated using the software TRNSYS® and, then, heating system performances are estimated through a simplified model based on the European Standard EN 15316. Several heating systems have been analyzed, evaluating: independent and centralized configurations, condensing and traditional boilers, radiator and radiant floor emitters and solar plant integration. The heating systems are applied to four buildings dating back to 2010, 2006, 1960s and 1930s. All the combinations of heating systems and buildings are analyzed in detail, evaluating efficiency and primary energy consumption. In most of the cases the choice between centralized and independent heating systems has minor effects on primary energy consumption, less than 3%: the introduction of condensing technology and the integration with solar heating plant can reduce energy consumption by 11% and 29%, respectively.

  8. Synergies between Urban Heat Island and Heat Waves in Athens (Greece), during an extremely hot summer (2012).

    Science.gov (United States)

    Founda, Dimitra; Santamouris, Mattheos

    2017-09-08

    Heat waves (HWs) are recognized as a serious threat for human health worldwide, with urban areas being more vulnerable due to the urban heat island (UHI) effect and population density. Yet, in the climate change context, HWs are becoming more frequent, stronger and longer, which, coupled with intensifying urbanization exacerbates thermal risk for urban residents. Despite the profound impact of this global phenomenon there is no clear consensus so far on possible synergies between UHIs and HWs. The study sheds light on the complex synergies between UHIs and HWs focusing on coastal sites. A quite challenging period comprising five HW episodes during summer 2012 in Athens (Greece) was selected for analysis. A positive feedback between UHIs and HWs was found, with intensification of the average UHI magnitude by up to 3.5 °C during HWs, compared to summer background conditions. Our results contribute significantly to understanding synergies between UHIs and HWs that may strongly increase thermal risk in cities and vulnerability of urban population.

  9. High power, high efficiency continuous-wave 808 nm laser diode arrays

    Science.gov (United States)

    Wang, Zhenfu; Li, Te; Yang, Guowen; Song, Yunfei

    2017-12-01

    The continuous-wave 100 W-class 808 nm laser diode arrays with extremely high power conversion efficiency of 68% were reported at the heatsink temperature of 25 °C. To the best of our knowledge, this was the highest power conversion efficiency at continuous-wave 106 W 808 nm laser diode array with 50% fill factor so far. An asymmetric broad waveguide epitaxial structure with very low internal optical loss of 0.5 cm-1 was presented. In order to improve the efficiency, various fill factor devices were studied. The 50 W laser diode array with 30% fill factoir and 1.0 mm cavity length demonstrated power conversion efficiency of 71% at heatsink temperature of 15 °C.

  10. Loop heating by D.C. electric current and electromagnetic wave emissions simulated by 3-D EM particle zone

    Science.gov (United States)

    Sakai, J. I.; Zhao, J.; Nishikawa, K.-I.

    1994-01-01

    We have shown that a current-carrying plasma loop can be heated by magnetic pinch driven by the pressure imbalance between inside and outside the loop, using a 3-dimensional electromagnetic (EM) particle code. Both electrons and ions in the loop can be heated in the direction perpendicular to the ambient magnetic field, therefore the perpendicular temperature can be increased about 10 times compared with the parallel temperature. This temperature anisotropy produced by the magnetic pinch heating can induce a plasma instability, by which high-frequency electromagnetic waves can be excited. The plasma current which is enhanced by the magnetic pinch can also excite a kinetic kink instability, which can heat ions perpendicular to the magnetic field. The heating mechanism of ions as well as the electromagnetic emission could be important for an understanding of the coronal loop heating and the electromagnetic wave emissions from active coronal regions.

  11. Heat Shock-Enhanced Conjugation Efficiency in Standard Campylobacter jejuni Strains.

    Science.gov (United States)

    Zeng, Ximin; Ardeshna, Devarshi; Lin, Jun

    2015-07-01

    Campylobacter jejuni, the leading bacterial cause of human gastroenteritis in the United States, displays significant strain diversity due to horizontal gene transfer. Conjugation is an important horizontal gene transfer mechanism contributing to the evolution of bacterial pathogenesis and antimicrobial resistance. It has been observed that heat shock could increase transformation efficiency in some bacteria. In this study, the effect of heat shock on C. jejuni conjugation efficiency and the underlying mechanisms were examined. With a modified Escherichia coli donor strain, different C. jejuni recipient strains displayed significant variation in conjugation efficiency ranging from 6.2 × 10(-8) to 6.0 × 10(-3) CFU per recipient cell. Despite reduced viability, heat shock of standard C. jejuni NCTC 11168 and 81-176 strains (e.g., 48 to 54°C for 30 to 60 min) could dramatically enhance C. jejuni conjugation efficiency up to 1,000-fold. The phenotype of the heat shock-enhanced conjugation in C. jejuni recipient cells could be sustained for at least 9 h. Filtered supernatant from the heat shock-treated C. jejuni cells could not enhance conjugation efficiency, which suggests that the enhanced conjugation efficiency is independent of secreted substances. Mutagenesis analysis indicated that the clustered regularly interspaced short palindromic repeats system and the selected restriction-modification systems (Cj0030/Cj0031, Cj0139/Cj0140, Cj0690c, and HsdR) were dispensable for heat shock-enhanced conjugation in C. jejuni. Taking all results together, this study demonstrated a heat shock-enhanced conjugation efficiency in standard C. jejuni strains, leading to an optimized conjugation protocol for molecular manipulation of this organism. The findings from this study also represent a significant step toward elucidation of the molecular mechanism of conjugative gene transfer in C. jejuni. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  12. Influence of scale deposit and its thickness on the heat exchanger operational efficiency

    Science.gov (United States)

    Kocharyan, E. V.; Skiba, E. D.; Levina, E. Y.

    2017-11-01

    Materials submitted provide for the research results of the problem of scale formation in heat exchangers and show results of calculations of scale type and thickness impact on heat transfer factor and on heat exchanger overall energy efficiency with regard to heat exchanger hydraulic resistance increase. Calculations have been carried out using the example of heat exchanger PV1 (∏B1) 219-2-G-1, 6-6-UZ, manufactured as per State Standard (GOST) 27590-2005. On the basis of calculations performed recommendations on maximum allowable thickness of scale crust of different type, after scaling of which the heat exchanger operation may infringe the technological process, have been elaborated.

  13. Social participation and heat-related behavior in older adults during heat waves and on other days.

    Science.gov (United States)

    Lindemann, Ulrich; Skelton, Dawn A; Oksa, Juha; Beyer, Nina; Rapp, Kilian; Becker, Clemens; Klenk, Jochen

    2017-11-06

    High indoor temperatures require behavioral adaptation, especially among vulnerable older adults. There are uncertainties as to the degree to which people adapt to these challenging conditions. The aim of this study was to describe the degree of adaptation of social participation and other heat-related behavior with respect to higher indoor temperatures. In this study 81 residents from 10 sheltered living facilities (84% women, mean age 80.9 years) were visited every 4 weeks from May to October 2015 and additionally during 2 heat waves in July and August 2015. The indoor temperature, drinking and clothing and social participation were documented. Baseline documentation of gait speed and residential area were used to create subgroups of people with high or low gait speed and with facility location in a garden city/suburb or city/city center. Social participation and clothing decreased with -4.53 in the World Health Organization participation score units (95% confidence interval CI -5.32; -3.74) and -0.41 for clothing units (95% CI -0.46; -0.37) and volume of drinking increased (0.65 l/day; 95% CI 0.52; 0.77) per increase of indoor temperature by 10 °C. The negative association between indoor temperature and social life participation was stronger if functional capacity was low or if the facility was located in the city/city center. Not all older adults displayed temperature-related adaptive behavior. For older adults the negative association between indoor temperature and social life participation was stronger in the city/city center or if their functional capacity was low. Frequent personal contact and motivation of those who are frail might be helpful to support their adaptive behavior of drinking and clothing during heat stress.

  14. Heat waves imposed during early pod development in soybean (Glycine max) cause significant yield loss despite a rapid recovery from oxidative stress.

    Science.gov (United States)

    Siebers, Matthew H; Yendrek, Craig R; Drag, David; Locke, Anna M; Rios Acosta, Lorena; Leakey, Andrew D B; Ainsworth, Elizabeth A; Bernacchi, Carl J; Ort, Donald R

    2015-08-01

    Heat waves already have a large impact on crops and are predicted to become more intense and more frequent in the future. In this study, heat waves were imposed on soybean using infrared heating technology in a fully open-air field experiment. Five separate heat waves were applied to field-grown soybean (Glycine max) in central Illinois, three in 2010 and two in 2011. Thirty years of historical weather data from Illinois were analyzed to determine the length and intensity of a regionally realistic heat wave resulting in experimental heat wave treatments during which day and night canopy temperatures were elevated 6 °C above ambient for 3 days. Heat waves were applied during early or late reproductive stages to determine whether and when heat waves had an impact on carbon metabolism and seed yield. By the third day of each heat wave, net photosynthesis (A), specific leaf weight (SLW), and leaf total nonstructural carbohydrate concentration (TNC) were decreased, while leaf oxidative stress was increased. However, A, SLW, TNC, and measures of oxidative stress were no different than the control ca. 12 h after the heat waves ended, indicating rapid physiological recovery from the high-temperature stress. That end of season seed yield was reduced (~10%) only when heat waves were applied during early pod developmental stages indicates the yield loss had more to do with direct impacts of the heat waves on reproductive process than on photosynthesis. Soybean was unable to mitigate yield loss after heat waves given during late reproductive stages. This study shows that short high-temperature stress events that reduce photosynthesis and increase oxidative stress resulted in significant losses to soybean production in the Midwest, U.S. The study also suggests that to mitigate heat wave-induced yield loss, soybean needs improved reproductive and photosynthetic tolerance to high but increasingly common temperatures. Published 2015. This article is a U.S. Government work and is

  15. Quantum efficiency bound for continuous heat engines coupled to noncanonical reservoirs

    Science.gov (United States)

    Agarwalla, Bijay Kumar; Jiang, Jian-Hua; Segal, Dvira

    2017-09-01

    We derive an efficiency bound for continuous quantum heat engines absorbing heat from squeezed thermal reservoirs. Our approach relies on a full-counting statistics description of nonequilibrium transport and it is not limited to the framework of irreversible thermodynamics. Our result, a generalized Carnot efficiency bound, is valid beyond the small-squeezing and high-temperature limit. Our findings are embodied in a prototype three-terminal quantum photoelectric engine where a qubit converts heat absorbed from a squeezed thermal reservoir into electrical power. We demonstrate that in the quantum regime, the efficiency can be greatly amplified by squeezing. From the fluctuation relation, we further receive other operational measures in linear response, for example, the universal maximum power efficiency bound.

  16. Heating efficiency of multi-walled carbon nanotubes in the first and second biological windows

    Science.gov (United States)

    Maestro, Laura Martínez; Haro-González, Patricia; Del Rosal, Blanca; Ramiro, Julio; Caamaño, A. J.; Carrasco, Elisa; Juarranz, Angeles; Sanz-Rodríguez, Francisco; Solé, José García; Jaque, Daniel

    2013-08-01

    Quantum dot based-thermometry, in combination with double beam confocal microscopy and infrared thermal imaging, has been used to investigate the heating efficiency of multi-walled carbon nanotubes (MWCNTs) under optical excitation within the first (808 nm) and second (1090 nm) biological windows as well as in the spectral region separating them (980 nm). It has been found that for the three excitation wavelengths the heating efficiency of MWCNTs (10 nm in diameter and 1.5 μm in length) is close to 50%. Despite this ``flat'' heating efficiency, we have found that the excitation wavelength is, indeed, critical during in vivo experiments due to the spectral dependence of both tissue absorption and scattering coefficients. It has been concluded that efficiency and selectivity of in vivo photothermal treatments based on MWCNTs are simultaneously optimized when laser irradiation lies within the first or second biological window.

  17. Fast wave current drive in neutral beam heated plasmas on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Petty, C.C.; Forest, C.B.; Pinsker, R.I.; deGrassie, J.S. [General Atomics, San Diego, California 92186 (United States); Baity, F.W. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Callis, R.W.; Cary, W.P.; Chiu, S.C.; Freeman, R.L.; Gohil, P.; Groebner, R.J.; Ikezi, H. [General Atomics, San Diego, California 92186 (United States); Jaeger, E.F. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Lin-Liu, Y.R. [General Atomics, San Diego, California 92186 (United States); Murakami, M. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Porkolab, M. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Prater, R. [General Atomics, San Diego, California 92186 (United States); Rice, B.W. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    1997-04-01

    The physics of non-inductive current drive and current profile control using the fast magnetosonic wave has been demonstrated on the DIII-D tokamak. In non-sawtoothing discharges formed by neutral beam injection (NBI), the radial profile of the fast wave current drive (FWCD) was determined by the response of the loop voltage profile to co, counter, and symmetric antenna phasings, and was found to be in good agreement with theoretical models. The application of counter FWCD increased the magnetic shear reversal of the plasma and delayed the onset of sawteeth, compared to co FWCD. The partial absorption of fast waves by energetic beam ions at high harmonics of the ion cyclotron frequency was also evident from a build up of fast particle pressure near the magnetic axis and a correlated increase in the neutron rate. The anomalous fast particle pressure and neutron rate increased with increasing NBI power and peaked when a harmonic of the deuterium cyclotron frequency passed through the center of the plasma. The experimental FWCD efficiency was highest at 2 T where the interaction between the fast waves and the beam ions was weakest; as the magnetic field strength was lowered, the FWCD efficiency decreased to approximately half of the maximum theoretical value. {copyright} {ital 1997 American Institute of Physics.}

  18. High-efficiency wideband reflection polarization conversion metasurface for circularly polarized waves

    Science.gov (United States)

    Huang, Xiaojun; Chen, Jiao; Yang, Helin

    2017-07-01

    Metasurfaces have opened an effective way to handle the polarization states of electromagnetic waves due to their intrinsic parameters which could be flexibly tailored. In this paper, we present a simple anisotropic metasurface to realize the polarization manipulation of circularly polarized waves with high conversion efficiency in a wide frequency range. The presented simple metasurface can keep the handedness of the reflected waves for circularly polarized incident waves. Both the simulated and experimental results show that the bandwidth of the polarization conversion ratio more than 90% is 7.16 GHz (8.16-15.32 GHz), and the polarization extinction ratio is larger than 15 dB in this frequency range. Because of the simple design and easy fabrication, the designed metasurface can be an excellent candidate for reflection circular polarization conversion.

  19. Could sulfate aerosol emissions be used for regional heat wave mitigation?

    Science.gov (United States)

    Bernstein, D.; Neelin, J.; Li, Q.; CHEN, D.

    2012-12-01

    Geoengineering applications by injection of sulfate aerosols into the stratosphere are under consideration as a measure of last resort to counter global warming. Here adaptation to a potential regional-scale application to offset the impacts of heat waves is critically examined. The effect of regional-scale sulfate aerosol emission over California in each of two days of the July 2006 heat wave using the Weather Research and Forecasting model with fully coupled chemistry (WRF-Chem) is used to quantify potential reductions in surface temperature as a function of emission rates in the lower stratosphere. Over the range considered, afternoon temperature reductions scale almost linearly with emissions. Local meteorological factors yield geographical differences in surface air temperature sensitivity. For emission rates of approximately 30 μ g m-2 s-1 of sulfate aerosols (with standard WRF-Chem size distribution) over the region, temperature decreases of around 7oC result during the middle part of the day over the Central Valley, one of the hardest hit by the heat wave. Regions more ventilated with oceanic air such as Los Angeles have slightly smaller reductions. The length of the hottest part of the day is also reduced. Advection effects on the aerosol cloud must be more carefully forecast for smaller emission regions. Verification of the impacts could be done via measurements of differences in reflected and surface downward shortwave. Such regional geoengineering applications with specific near-term target effects but smaller cost and side effects could potentially provide a means of testing larger scale applications. However, design trade-offs differ from global applications and the size of the required emissions and the necessity of emission close to the target region raise substantial concerns. The evaluation of this regional scale application is thus consistent with global model evaluations emphasizing that mitigation via reduction of fossil fuels remains

  20. IMPROVING THE EFFICIENCY OF THE HEATING SYSTEM FOR PUBLIC BUILDINGS INFRASTRUCTURE IN THE CONTEXT OF DNURT

    Directory of Open Access Journals (Sweden)

    O. M. Pshinko

    2016-06-01

    Full Text Available Purpose. The paper analyses the possibility and terms of increasing the efficiency of heating and ventilation systems of public buildings at the present stage of development and the specific climatic conditions of Ukraine. The main purpose is to develop specific measures for public buildings, which will lead to a significant reduction in energy costs for heating and air conditioning system. The example is similar system of DNURT compact campus, which is heated with its own autonomous boiler that uses natural gas. Methodology. The statistical heat loss analysis for the last 5 years allows defining the types and calculating the heat loss values for specific conditions. These losses are compared with those in the world practice and based on the comparison and analysis of the current system there are offered the ways to reduce the heat loss values through the use of various technical and organizational methods.The paper also proposes involvement for this purpose of secondary and alternative energy sources. The secondary energy resources include the heat that is emitted by people and that coming out with the air during ventilation of buildings. The renewable sources include solar and geothermal energy. To enhance the heat transfer medium temperature capacity it is proposed to use the heat pumps. Findings. The maximum possible use of the proposed measures and implementation of rational schematic and engineering solutions for heat and hot water supply systems cam reduce the energy loss for heating and hot water by 30-35%. Originality. The paper for the first time proposed the use of new integrated approaches to maintain the desired heat balance in the winter period, as well as the new schematic solutions for heating and ventilation systems, both in winter and in summer, based on the use of heat pumps and secondary energy resources. Practical value. The introduction of the proposed schematic solutions and approaches demand relatively small capital

  1. Heat transfer efficiency in grate burning of wood chips - challenges and practical limitations

    Energy Technology Data Exchange (ETDEWEB)

    Rousku, P.

    2009-07-01

    Small-scale grate boilers are typical way of utilizing wood chips nowadays. Boilers in output capacity range of 0.5-3 MW have become more and more general during recent years throughout Europe and in Finland. The combustion technique details vary a lot depending on the equipment manufacturer and boiler capacity. The practical experiences in Finland show that the boiler design is in relatively good level, but the natural conditions in the Nordic countries sometimes cause difficulties in sustaining homogeneous wood chip quality. Then, this causes drastic, quick changes in the combustion conditions. This leads to dirty smoke gases and disturbance in the heat transfer in the boiler convector. This study aims at presenting these practical factors affecting the heat transfer efficiency and some ideas to avoid the problems. Also the boiler plant technology aiming at combined heat and power production in small scale implies very efficient heat transfer. The most important single factor enabling or preventing efficient heat transfer in the boiler lies in forest sand then in wood chip storages. The wood chip quality consists of homogeneous moisture content, particle size and energy content. If these factors alter uncontrollably, this causes: temperature decrease on the grate and in the flame; increase in the smoke gas flow due to increased vapour content; increased impurities in the smoke gas. These all sakes cause major contamination of the heat exchanger and thus decrease in the heat transfer efficiency. Also some technically critical details can be pointed out. Among others, these are: old-fashioned, slowly and roughly reacting automation and combustion adjustment; primary and secondary combustion air feed division and points; boiler vacuum control; combustion chamber structure and amount of masonry. Wood chip boiler heat transfer efficiency can be improved by answering to above mentioned sakes. Absolutely the most important thing is to train the forest fuel production

  2. Energy Efficiency of Low-Temperature Deaeration of Makeup Water for a District Heating System

    Energy Technology Data Exchange (ETDEWEB)

    Sharapov, V. I., E-mail: vlad-sharapov2008@yandex.ru; Kudryavtseva, E. V. [Ulyanovsk State Technical University (Russian Federation)

    2016-07-15

    It is shown that the temperature of makeup water in district heating systems has a strong effect on the energy efficiency of turbines of thermal power plants. A low-temperature deaeration process that considerably improves the energy efficiency of thermal power plants is developed. The desorbing agent is the gas supplied to the burners of the boiler. The energy efficiency of the process for a typical unit of thermal power plant is assessed.

  3. Efficient district heating in the future energy system. Final report; Effektiv fjernvarme i fremtidens energisystem. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    2009-07-01

    The purpose of this project is to illustrate how district heating can develop its role in the future Danish energy system, for example by reducing energy losses and the dynamic use of common technologies such as cogeneration and heat storage, and less widespread technologies such as heat pumps, geothermal heating, and cooling. The aim is also to analyse how electricity and district heating can interact more effectively, and to point out how framework conditions are important for district heating's continued development and efficiency. In the project, a linear optimization model is developed and applied as to analyse the interaction between district heating supply on the one hand, and energy savings, CO{sub 2} targets, wind power and the international electricity market on the other hand. Furthermore, more close-case operational analyses of district heating systems have been made in Ringkoebing and the metropolitan area, based on data from the district heating companies. Finally, a wide range of challenges for district heating in the long term were discussed and analysed during meetings with the project's reference group, including the need for development and demonstration projects. (ln)

  4. A hybrid version of swan for fast and efficient practical wave modelling

    NARCIS (Netherlands)

    M. Genseberger (Menno); J. Donners

    2016-01-01

    htmlabstractIn the Netherlands, for coastal and inland water applications, wave modelling with SWAN has become a main ingredient. However, computational times are relatively high. Therefore we investigated the parallel efficiency of the current MPI and OpenMP versions of SWAN. The MPI version is

  5. Efficient Femtosecond Mid-infrared Pulse Generation by Dispersive Wave Radiation in Bulk Lithium Niobate Crystal

    DEFF Research Database (Denmark)

    Zhou, Binbin; Guo, Hairun; Bache, Morten

    2014-01-01

    We experimentally demonstrate efficient mid-infrared pulse generation by dispersive wave radiation in bulk lithium niobate crystal. Femtosecond mid-IR pulses centering from 2.8-2.92 μm are generated using the single pump wavelengths from 1.25-1.45 μm. © 2014 Optical Society of America...

  6. The 2010 Pakistan Flood and the Russia Heat Wave: Teleconnection of Extremes

    Science.gov (United States)

    Lau, William K.; Kim, K. M.

    2010-01-01

    The Pakistan flood and the Russia heat wave/Vvild fires of the summer of2010 were two of the most extreme, and catastrophic events in the histories of the two countries occurring at about the same time. To a casual observer, the timing may just be a random coincidence of nature, because the two events were separated by long distances, and represented opposite forces of nature, i.e., flood vs. drought, and water vs. fire. In this paper, using NASA satellite and NOAA reanalysis data, we presented observation evidences that that the two events were indeed physically connected.

  7. Heat transfer from vapor condensation in the region behind a shock wave

    Science.gov (United States)

    Kobayashi, Yasunori; Oshiro, Naoto

    1989-06-01

    A series of experiments were conducted on shock wave propagation in a single-component two-phase(vapor-liquid) medium. A heat transfer mechanism in the flow field associated with vapor condensation behind a shock front was investigated. Measurements of pressure and temperature were made by conventional sensors and the flow field was visualized by schlieren photographs with the aid of high speed drum camera. Refrigerant-11 and benzene were used as a working fluid under a large void fraction of almost 100 percent. A flow field realized behind a shock front revealed significant features of ineffective compressibility and complicated flow patterns, which are largely different from those of pure gases.

  8. Demonstration of Efficient Core Heating of Magnetized Fast Ignition in FIREX project

    Science.gov (United States)

    Johzaki, Tomoyuki

    2017-10-01

    Extensive theoretical and experimental research in the FIREX ``I project over the past decade revealed that the large angular divergence of the laser generated electron beam is one of the most critical problems inhibiting efficient core heating in electron-driven fast ignition. To solve this problem, beam guiding using externally applied kilo-tesla class magnetic field was proposed, and its feasibility has recently been numerically demonstrated. In 2016, integrated experiments at ILE Osaka University demonstrated core heating efficiencies reaching > 5 % and heated core temperatures of 1.7 keV. In these experiments, a kilo-tesla class magnetic field was applied to a cone-attached Cu(II) oleate spherical solid target by using a laser-driven capacitor-coil. The target was then imploded by G-XII laser and heated by the PW-class LFEX laser. The heating efficiency was evaluated by measuring the number of Cu-K- α photons emitted. The heated core temperature was estimated by the X-ray intensity ratio of Cu Li-like and He-like emission lines. To understand the detailed dynamics of the core heating process, we carried out integrated simulations using the FI3 code system. Effects of magnetic fields on the implosion and electron beam transport, detailed core heating dynamics, and the resultant heating efficiency and core temperature will be presented. I will also discuss the prospect for an ignition-scale design of magnetized fast ignition using a solid ball target. This work is partially supported by JSPA KAKENHI Grant Number JP16H02245, JP26400532, JP15K21767, JP26400532, JP16K05638 and is performed with the support and the auspices of the NIFS Collaboration Research program (NIFS12KUGK057, NIFS15KUGK087).

  9. Simulation of High-Harmonic Fast-Wave Heating on the National Spherical Tokamak Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Green, David L [ORNL; Jaeger, Erwin Frederick [ORNL; Chen, Guangye [ORNL; Berry, Lee A [ORNL; Pugmire, Dave [ORNL; Canik, John [ORNL; Ryan, Philip Michael [ORNL

    2011-01-01

    Images associated with radio-frequency heating of low-confinement mode plasmas in the National Spherical Tokamak Experiment, as calculated by computer simulation, are presented. The AORSA code has been extended to simulate the whole antenna-to-plasma heating system by including both the kinetic physics of the well-confined core plasma and a poorly confined scrape-off plasma and vacuum vessel structure. The images presented show the 3-D electric wave field amplitude for various antenna phasings. Visualization of the simulation results in 3-D makes clear that -30 degrees phasing excites kilo-volt per meter coaxial standing modes in the scrape-off plasma and shows magnetic-field-aligned whispering-gallery type modes localized to the plasma edge.

  10. Efficiency of Passive Utilization of Ground “Cold” in Adaptive Geothermal Heat Pump Heating and Cooling Systems (AGHCS

    Directory of Open Access Journals (Sweden)

    Vasilyev G.P.

    2016-01-01

    Full Text Available This article deals with estimating a potential and efficiency of utilization of passive ground “cold” for cooling buildings in climatic conditions of Moscow (Russia. The article presents results of numerical analysis to assess the efficiency of reducing peak cooling loads of the building equipped with AGHCS, through the utilization of natural cold of wells for passive cooling and cold storage in summer at night (off-peak time with its subsequent consumption in the day time, both in passive mode, and with heat pumps. The conclusions of the article set out the basic principles of passive cooling in the design of AGHCS.

  11. Mitochondrial efficiency and exercise economy following heat stress: a potential role of uncoupling protein 3.

    Science.gov (United States)

    Salgado, Roy M; Sheard, Ailish C; Vaughan, Roger A; Parker, Daryl L; Schneider, Suzanne M; Kenefick, Robert W; McCormick, James J; Gannon, Nicholas P; Van Dusseldorp, Trisha A; Kravitz, Len R; Mermier, Christine M

    2017-02-01

    Heat stress has been reported to reduce uncoupling proteins (UCP) expression, which in turn should improve mitochondrial efficiency. Such an improvement in efficiency may translate to the systemic level as greater exercise economy. However, neither the heat-induced improvement in mitochondrial efficiency (due to decrease in UCP), nor its potential to improve economy has been studied. Determine: (i) if heat stress in vitro lowers UCP3 thereby improving mitochondrial efficiency in C2C12 myocytes; (ii) whether heat acclimation (HA) in vivo improves exercise economy in trained individuals; and (iii) the potential improved economy during exercise at altitude. In vitro, myocytes were heat stressed for 24 h (40°C), followed by measurements of UCP3, mitochondrial uncoupling, and efficiency. In vivo, eight trained males completed: (i) pre-HA testing; (ii) 10 days of HA (40°C, 20% RH); and (iii) post-HA testing. Pre- and posttesting consisted of maximal exercise test and submaximal exercise at two intensities to assess exercise economy at 1600 m (Albuquerque, NM) and 4350 m. Heat-stressed myocytes displayed significantly reduced UCP3 mRNA expression and, mitochondrial uncoupling (77.1 ± 1.2%, P economy did not change at low and moderate exercise intensities. Our findings indicate that while heat-induced reduction in UCP3 improves mitochondrial efficiency in vitro, this is not translated to in vivo improvement of exercise economy at 1600 m or 4350 m. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  12. The relationship between housing and heat wave resilience in older people

    Science.gov (United States)

    Loughnan, Margaret; Carroll, Matthew; Tapper, Nigel J.

    2015-09-01

    Older people have justifiably been highlighted as a high-risk group with respect to heat wave mortality and morbidity. However, there are older people living within the community who have developed adaptive and resilient environments around their home that provide some protection during periods of extreme heat. This study investigated the housing stock and self-reported thermal comfort of a group of older people living in a regional town in Australia during the summer of 2012. The results indicated that daily maximum living room temperature was not significantly correlated with outdoor temperature, and daily minimum living room temperature was very weakly correlated with outdoor temperature. Residents reported feeling comfortable when indoor temperature approximated 26 °C. As living room temperature increased, indoor thermal comfort decreased. Significant differences between indoor temperatures were noted for homes that were related to house characteristics such as the age of the house, the number of air-conditioning units, the pitch of the roof, home insulation and the number of heat-mitigation modifications made to the home. Brick veneer homes showed smaller diurnal changes in temperature than other building materials. With population ageing and the increasing focus on older people living in the community, the quality of the housing stock available to them will influence their risk of heat exposure during extreme weather.

  13. Fan cycling strategies and heat pipe heat exchangers provide energy efficient dehumidification

    Energy Technology Data Exchange (ETDEWEB)

    Shirey, D.B. III [Florida Solar Energy Center, Cape Canaveral, FL (United States)

    1995-03-01

    This article describes two methods to reduce energy consumption and peak demand in buildings that require humidity control that were demonstrated at the Salvador Dali Museum in St. Petersburg, Florida. The first method centered on alternative indoor fan cycling strategies and the second method involved the use of heat pipe heat exchangers. Both approaches increased the dehumidification performance of the existing air-conditioning systems and provided substantial savings. Simple, low cost alternative fan cycling strategies were used. When possible, auto fan control replaced constant fan operation to avoid excess fan energy consumption, ventilation load and compressor operation. The alternative fan control strategies reduced indoor humidity fluctuations in all zones, and significantly reduced overall humidity levels in the museum lobby and storage area. An HPHX was installed within one of the two gallery RTUs to improve the unit`s dehumidification performance. The passive HPHX significantly reduced electric reheat and compressor operation while maintaining the precise temperature and humidity requirements within the gallery. The second gallery RTU now operates primarily as a back-up unit to the heat pipe-assisted air-conditioning unit.

  14. Numerical study of heating the upper atmosphere by acoustic-gravity waves from a local source on the Earth's surface and influence of this heating on the wave propagation conditions

    Science.gov (United States)

    Karpov, I. V.; Kshevetskii, S. P.

    2017-11-01

    The propagation of acoustic-gravity waves (AGW) from a source on the Earth's surface to the upper atmosphere is investigated with methods of mathematical modeling. The applied non-linear model of wave propagation in the atmosphere is based on numerical integration of a complete set of two-dimensional hydrodynamic equations. The source on the Earth's surface generates waves with frequencies near to the Brunt-Vaisala frequency. The results of simulation have revealed that some region of heating the atmosphere by propagated upward and dissipated AGWs arises above the source at altitudes nearby of 200 km. The horizontal scale of this heated region is about 1000 km in the case of the source that radiates AGWs during approximately 1 h. The appearing of the heated region has changed the conditions of AGW propagation in the atmosphere. When the heated region in the upper atmosphere has been formed, further a waveguide regime of propagation of waves with the periods shorter the Brunt-Vaisala period is realized. The upper boundary of the wave-guide coincides with the arisen heated region in the upper atmosphere. The considered mechanism of formation of large-scale disturbances in the upper atmosphere may be useful for explanation of connections of processes in the upper and lower atmospheric layers.

  15. Heat waves imposed during early pod development in soybean (Glycine max) cause significant yield loss despite a rapid recovery from oxidative stress

    Science.gov (United States)

    This study is the first field based experiment that uses IR heaters to study the effects of a regionally defined heat wave on soybean physiology and productivity. The heating technology was successful and all of the heat waves were maintained at the target temperature for the three day duration of t...

  16. Effect on the load size on the efficiency of microwave heating under stop flow and continuous flow conditions

    NARCIS (Netherlands)

    Patil, N.G.; Rebrov, E.V.; Esveld, D.C.; Eränen, K.; Benaskar, F.; Meuldijk, Jan; Mikkola, J.P.; Hessel, V.; Hulshof, L.A.; Murzin, D.Y.; Schouten, J.C.

    2012-01-01

    A novel heating efficiency analysis of the microwave heated stop-flow (i.e. stagnant
    liquid) and continuous-flow reactors has been presented. The thermal losses to the surrounding
    air by natural convection have been taken into account for heating efficiency calculation of
    the microwave

  17. Methods of Assessing the Efficiency of Cogeneration of Electricity and Heat

    Directory of Open Access Journals (Sweden)

    Postolaty V.M.

    2015-12-01

    Full Text Available A method that allows calculating the primary energy savings of fuel cogeneration of electricity and heat as compared to separate methods produce the same amount of these types of energy. An analytic expression relating the energy consumption of fuel for production of electricity and heat, taking into account the efficiency with the technologies of production of electricity and heat separately, and the total efficiency when these types of energy are in cogeneration. The results are illustrated by the example. Basing on these results it is recommended to amend the Law on thermal energy and cogeneration of electricity and heat concerning the methodologies for calculating performance of these types of energy cogeneration.

  18. Solutions for Energy Efficient and Sustainable Heating of Ventilation Air: A Review

    Directory of Open Access Journals (Sweden)

    A. Žandeckis

    2015-10-01

    Full Text Available A high energy efficiency and sustainability standards defined by modern society and legislation requires solutions in the form of complex integrated systems. The scope of this work is to provide a review on technologies and methods for the heating of ventilation air as a key aspect for high energy and environmental performance of buildings located in a cold climate. The results of this work are more relevant in the buildings where space heating consumes a significant part of the energy balance of a building, and air exchange is arranged in an organized manner. A proper design and control strategy, heat recovery, the use of renewable energy sources, and waste heat are the main aspects which must be considered for efficient and sustainable ventilation. This work focuses on these aspects. Air conditioning is not in the scope of this study.

  19. Similarity solution for the flow behind a shock wave in a non-ideal gas with heat conduction and radiation heat-flux in magnetogasdynamics

    Science.gov (United States)

    Nath, G.; Vishwakarma, J. P.

    2014-05-01

    The propagation of a spherical (or cylindrical) shock wave in a non-ideal gas with heat conduction and radiation heat-flux, in the presence of a spacially decreasing azimuthal magnetic field, driven out by a moving piston is investigated. The heat conduction is expressed in terms of Fourier's law and the radiation is considered to be of the diffusion type for an optically thick grey gas model. The thermal conductivity K and the absorption coefficient αR are assumed to vary with temperature and density. The gas is assumed to have infinite electrical conductivity and to obey a simplified van der Waals equation of state. The shock wave moves with variable velocity and the total energy of the wave is non-constant. Similarity solutions are obtained for the flow-field behind the shock and the effects of variation of the heat transfer parameters, the parameter of the non-idealness of the gas, both, decreases the compressibility of the gas and hence there is a decrease in the shock strength. Further, it is investigated that with an increase in the parameters of radiative and conductive heat transfer the tendency of formation of maxima in the distributions of heat flux, density and isothermal speed of sound decreases. The pressure and density vanish at the inner surface (piston) and hence a vacuum is form at the center of symmetry. The shock waves in conducting non-ideal gas with conductive and radiative heat fluxes can be important for description of shocks in supernova explosions, in the study of central part of star burst galaxies, nuclear explosion, chemical detonation, rupture of a pressurized vessels, in the analysis of data from exploding wire experiments, and cylindrically symmetric hypersonic flow problems associated with meteors or reentry vehicles, etc. The findings of the present works provided a clear picture of whether and how the non-idealness parameter, conductive and radiative heat transfer parameters and the magnetic field affect the flow behind the shock

  20. Gravity Waves and Wind-Farm Efficiency in Neutral and Stable Conditions

    Science.gov (United States)

    Allaerts, Dries; Meyers, Johan

    2017-10-01

    We use large-eddy simulations (LES) to investigate the impact of stable stratification on gravity-wave excitation and energy extraction in a large wind farm. To this end, the development of an equilibrium conventionally neutral boundary layer into a stable boundary layer over a period of 8 h is considered, using two different cooling rates. We find that turbulence decay has considerable influence on the energy extraction at the beginning of the boundary-layer transition, but afterwards, energy extraction is dominated by geometrical and jet effects induced by an inertial oscillation. It is further shown that the inertial oscillation enhances gravity-wave excitation. By comparing LES results with a simple one-dimensional model, we show that this is related to an interplay between wind-farm drag, variations in the Froude number and the dispersive effects of vertically-propagating gravity waves. We further find that the pressure gradients induced by gravity waves lead to significant upstream flow deceleration, reducing the average turbine output compared to a turbine in isolated operation. This leads us to the definition of a non-local wind-farm efficiency, next to a more standard wind-farm wake efficiency, and we show that both can be of the same order of magnitude. Finally, an energy flux analysis is performed to further elucidate the effect of gravity waves on the flow in the wind farm.

  1. Hybrid Resonant Acoustics: Exploiting a New Class of Sound Waves for Highly Efficient Microfluidic Nebulisation

    Science.gov (United States)

    Rezk, Amgad; Yeo, Leslie

    2017-11-01

    A longstanding convention in acoustomicrofluidic manipulation-a consequence of wholesale adoption from decades long application of surface acoustic waves (SAWs) in electronics and telecommunications-has been to employ pure SAWs by eliminating wave reflections and bulk resonances in single crystal piezoelectric substrates with the assumption that this provides the most efficient way to actuate or manipulate fluid flow at microscale dimensions. Despite the many advantages of SAW microfluidics, particularly for aerosolising and hence delivering next generation macromolecular-based therapeutics via inhalation, the limitation of the SAW devices, however, lies in the input power it can sustain, thus constraining the nebulisation rates that can be generated, which has, among other things, severely hampered its practical adoption in pulmonary drug administration to date. Here, we unravel the existence of a surface reflected bulk wave (SRBW)-the first new class of sound waves to have been discovered in well over five decades-and show, quite counterintuitively, that it is possible to obtain an order-of-magnitude improvement in microfluidic manipulation efficiency through this unique hybrid combination of surface and bulk waves without increasing complexity or cost.

  2. Gravity Waves and Wind-Farm Efficiency in Neutral and Stable Conditions

    Science.gov (United States)

    Allaerts, Dries; Meyers, Johan

    2018-02-01

    We use large-eddy simulations (LES) to investigate the impact of stable stratification on gravity-wave excitation and energy extraction in a large wind farm. To this end, the development of an equilibrium conventionally neutral boundary layer into a stable boundary layer over a period of 8 h is considered, using two different cooling rates. We find that turbulence decay has considerable influence on the energy extraction at the beginning of the boundary-layer transition, but afterwards, energy extraction is dominated by geometrical and jet effects induced by an inertial oscillation. It is further shown that the inertial oscillation enhances gravity-wave excitation. By comparing LES results with a simple one-dimensional model, we show that this is related to an interplay between wind-farm drag, variations in the Froude number and the dispersive effects of vertically-propagating gravity waves. We further find that the pressure gradients induced by gravity waves lead to significant upstream flow deceleration, reducing the average turbine output compared to a turbine in isolated operation. This leads us to the definition of a non-local wind-farm efficiency, next to a more standard wind-farm wake efficiency, and we show that both can be of the same order of magnitude. Finally, an energy flux analysis is performed to further elucidate the effect of gravity waves on the flow in the wind farm.

  3. Instantaneous and efficient surface wave excitation of a low pressure gas or gases

    Science.gov (United States)

    Levy, Donald J.; Berman, Samuel M.

    1988-01-01

    A system for instantaneously ionizing and continuously delivering energy in the form of surface waves to a low pressure gas or mixture of low pressure gases, comprising a source of rf energy, a discharge container, (such as a fluorescent lamp discharge tube), an rf shield, and a coupling device responsive to rf energy from the source to couple rf energy directly and efficiently to the gas or mixture of gases to ionize at least a portion of the gas or gases and to provide energy to the gas or gases in the form of surface waves. The majority of the rf power is transferred to the gas or gases near the inner surface of the discharge container to efficiently transfer rf energy as excitation energy for at least one of the gases. The most important use of the invention is to provide more efficient fluorescent and/or ultraviolet lamps.

  4. The Misselhorn Cycle: Batch-Evaporation Process for Efficient Low-Temperature Waste Heat Recovery

    Directory of Open Access Journals (Sweden)

    Moritz Gleinser

    2016-05-01

    Full Text Available The concept of the Misselhorn cycle is introduced as a power cycle that aims for efficient waste heat recovery of temperature sources below 100 °C. The basic idea shows advantages over a standard Organic Rankine Cycle (ORC in overall efficiency and utilization of the heat source. The main characteristic of this cycle is the use of at least three parallel batch evaporators instead of continuous heat exchangers. The operational phases of the evaporators are shifted so that there is always one vaporizer in discharge mode. A transient MATLAB® model (The MathWorks: Natick, MA, USA is used to simulate the achievable performance of the Misselhorn cycle. The calculations of the thermodynamic states of the system are based on the heat flux, the equations for energy conservation and the equations of state found in the NIST Standard Reference Database 23 (Reference Fluid Thermodynamic and Transport Properties - REFPROP, National Institute of Standards and Technology: Gaithersburg, MD, USA. In the isochoric batch evaporation, the pressure and the corresponding boiling temperature rise over time. With a gradually increasing boiling temperature, no pinch point limitation occurs. Furthermore, the heat source medium is passed through the evaporators in serial order to obtain a quasi-counter flow setup. It could be shown that these features offer the possibility to gain both high thermal efficiencies and an enhanced utilization of the heat source at the same time. A basic model with a fixed estimated heat transfer coefficient promises a possible system exergy efficiency of 44.4%, which is an increase of over 60% compared to a basic ORC with a system exergy efficiency of only 26.8%.

  5. Marine Heat Waves and Their Impacts on Fisheries and Marine Ecosystems

    Science.gov (United States)

    Bond, N. A.

    2016-12-01

    Recent years have featured some prominent warm ocean events, also known as marine heat waves. Notable examples occurred in the northwest Atlantic in 2012, in the northeast Pacific in 2014-16, and of course, in the tropical Pacific in association with the 2015-16 El Nino. These episodic events can have profound impacts on marine ecosystems, with implications for fisheries. This paper will review the mechanistic linkages between marine heat waves and living marine resources drawing mostly on examples from the Pacific Ocean. Typically these events cause changes at lower-trophic levels that then ripple through the food web, i.e., are cases of bottom-up forcing. But how this happens varies regionally with the background oceanography, and the oceanographic properties crucial to the ecosystem. Because the effects of warm episodes can be substantial, their ramifications on ecosystems and fisheries are important from a host of perspectives (economic, conservation, cultural, etc.). In addition, to a certain extent they can provide insight into how marine ecosystems are liable to respond to global climate change.

  6. High-frequency torsional Alfvén waves as an energy source for coronal heating

    Science.gov (United States)

    Srivastava, Abhishek Kumar; Shetye, Juie; Murawski, Krzysztof; Doyle, John Gerard; Stangalini, Marco; Scullion, Eamon; Ray, Tom; Wójcik, Dariusz Patryk; Dwivedi, Bhola N.

    2017-03-01

    The existence of the Sun’s hot atmosphere and the solar wind acceleration continues to be an outstanding problem in solar-astrophysics. Although magnetohydrodynamic (MHD) modes and dissipation of magnetic energy contribute to heating and the mass cycle of the solar atmosphere, yet direct evidence of such processes often generates debate. Ground-based 1-m Swedish Solar Telescope (SST)/CRISP, Hα 6562.8 Å observations reveal, for the first time, the ubiquitous presence of high frequency (~12-42 mHz) torsional motions in thin spicular-type structures in the chromosphere. We detect numerous oscillating flux tubes on 10 June 2014 between 07:17 UT to 08:08 UT in a quiet-Sun field-of-view of 60” × 60” (1” = 725 km). Stringent numerical model shows that these observations resemble torsional Alfvén waves associated with high frequency drivers which contain a huge amount of energy (~105 W m-2) in the chromosphere. Even after partial reflection from the transition region, a significant amount of energy (~103 W m-2) is transferred onto the overlying corona. We find that oscillating tubes serve as substantial sources of Alfvén wave generation that provide sufficient Poynting flux not only to heat the corona but also to originate the supersonic solar wind.

  7. Comparison between off-resonance and electron Bernstein waves heating regime in a microwave discharge ion source

    Energy Technology Data Exchange (ETDEWEB)

    Castro, G.; Di Giugno, R.; Miracoli, R. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Universita degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S. Sofia 64, 95123 Catania (Italy); Mascali, D. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Romano, F. P. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); CNR-IBAM Via Biblioteca 4, 95124 Catania (Italy); Celona, L.; Gammino, S.; Lanaia, D.; Ciavola, G. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Serafino, T. [CSFNSM, Viale A. Doria 6, 95125 Catania (Italy); Di Bartolo, F. [Universita di Messina, Ctr. da Papardo-Sperone, 98100 Messina (Italy); Gambino, N. [INFN- Laboratori Nazionali del Sud, via S. Sofia 62, 95123 Catania (Italy); Universita degli Studi di Catania, Dipartimento di Fisica e Astronomia, V. S. Sofia 64, 95123 Catania (Italy); IET-Institute of Energy Technology, LEC-Laboratory for Energy Conversion, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich (Switzerland)

    2012-02-15

    A microwave discharge ion source (MDIS) operating at the Laboratori Nazionali del Sud of INFN, Catania has been used to compare the traditional electron cyclotron resonance (ECR) heating with an innovative mechanisms of plasma ignition based on the electrostatic Bernstein waves (EBW). EBW are obtained via the inner plasma electromagnetic-to-electrostatic wave conversion and they are absorbed by the plasma at cyclotron resonance harmonics. The heating of plasma by means of EBW at particular frequencies enabled us to reach densities much larger than the cutoff ones. Evidences of EBW generation and absorption together with X-ray emissions due to high energy electrons will be shown. A characterization of the discharge heating process in MDISs as a generalization of the ECR heating mechanism by means of ray tracing will be shown in order to highlight the fundamental physical differences between ECR and EBW heating.

  8. Control apparatus and method for efficiently heating a fuel processor in a fuel cell system

    Science.gov (United States)

    Doan, Tien M.; Clingerman, Bruce J.

    2003-08-05

    A control apparatus and method for efficiently controlling the amount of heat generated by a fuel cell processor in a fuel cell system by determining a temperature error between actual and desired fuel processor temperatures. The temperature error is converted to a combustor fuel injector command signal or a heat dump valve position command signal depending upon the type of temperature error. Logic controls are responsive to the combustor fuel injector command signals and the heat dump valve position command signal to prevent the combustor fuel injector command signal from being generated if the heat dump valve is opened or, alternately, from preventing the heat dump valve position command signal from being generated if the combustor fuel injector is opened.

  9. Summer heat waves over western Europe 1880-2003, their relationship to large-scale forcings and predictability

    Energy Technology Data Exchange (ETDEWEB)

    Della-Marta, P.M. [University of Bern, Institute of Geography, Climatology and Meteorology Research Group, Bern (Switzerland); Federal Office for Meteorology and Climatology MeteoSwiss, Zurich (Switzerland); National Climate Center, Bureau of Meteorology, Melbourne (Australia); Luterbacher, J.; Xoplaki, E.; Wanner, H. [University of Bern, Institute of Geography, Climatology and Meteorology Research Group, Bern (Switzerland); NCCR Climate, Bern (Switzerland); Weissenfluh, H. von [University of Bern, Institute of Geography, Climatology and Meteorology Research Group, Bern (Switzerland); Brunet, M. [University Rovira i Virgili, Climate Change Research Group, Tarragona (Spain)

    2007-08-15

    We investigate the large-scale forcing and teleconnections between atmospheric circulation (sea level pressure, SLP), sea surface temperatures (SSTs), precipitation and heat wave events over western Europe using a new dataset of 54 daily maximum temperature time series. Forty four of these time series have been homogenised at the daily timescale to ensure that the presence of inhomogeneities has been minimised. The daily data have been used to create a seasonal index of the number of heat waves. Using canonical correlation analysis (CCA), heat waves over western Europe are shown to be related to anomalous high pressure over Scandinavia and central western Europe. Other forcing factors such as Atlantic SSTs and European precipitation, the later as a proxy for soil moisture, a known factor in strengthening land-atmosphere feedback processes, are also important. The strength of the relationship between summer SLP anomalies and heat waves is improved (from 35%) to account for around 46% of its variability when summer Atlantic and Mediterranean SSTs and summer European precipitation anomalies are included as predictors. This indicates that these predictors are not completely collinear rather that they each have some contribution to accounting for summer heat wave variability. However, the simplicity and scale of the statistical analysis masks this complex interaction between variables. There is some useful predictive skill of summer heat waves using multiple lagged predictors. A CCA using preceding winter North Atlantic SSTs and preceding January to May Mediterranean total precipitation results in significant hindcast (1972-2003) Spearman rank correlation skill scores up to 0.55 with an average skill score over the domain equal to 0.28 {+-} 0.28. In agreement with previous studies focused on mean summer temperature, there appears to be some predictability of heat wave events on the decadal scale from the Atlantic Multidecadal Oscillation (AMO), although the long

  10. Summer heat waves over western Europe 1880 2003, their relationship to large-scale forcings and predictability

    Science.gov (United States)

    Della-Marta, P. M.; Luterbacher, J.; von Weissenfluh, H.; Xoplaki, E.; Brunet, M.; Wanner, H.

    2007-08-01

    We investigate the large-scale forcing and teleconnections between atmospheric circulation (sea level pressure, SLP), sea surface temperatures (SSTs), precipitation and heat wave events over western Europe using a new dataset of 54 daily maximum temperature time series. Forty four of these time series have been homogenised at the daily timescale to ensure that the presence of inhomogeneities has been minimised. The daily data have been used to create a seasonal index of the number of heat waves. Using canonical correlation analysis (CCA), heat waves over western Europe are shown to be related to anomalous high pressure over Scandinavia and central western Europe. Other forcing factors such as Atlantic SSTs and European precipitation, the later as a proxy for soil moisture, a known factor in strengthening land atmosphere feedback processes, are also important. The strength of the relationship between summer SLP anomalies and heat waves is improved (from 35%) to account for around 46% of its variability when summer Atlantic and Mediterranean SSTs and summer European precipitation anomalies are included as predictors. This indicates that these predictors are not completely collinear rather that they each have some contribution to accounting for summer heat wave variability. However, the simplicity and scale of the statistical analysis masks this complex interaction between variables. There is some useful predictive skill of summer heat waves using multiple lagged predictors. A CCA using preceding winter North Atlantic SSTs and preceding January to May Mediterranean total precipitation results in significant hindcast (1972 2003) Spearman rank correlation skill scores up to 0.55 with an average skill score over the domain equal to 0.28 ± 0.28. In agreement with previous studies focused on mean summer temperature, there appears to be some predictability of heat wave events on the decadal scale from the Atlantic Multidecadal Oscillation (AMO), although the long

  11. The short-term effect of heat waves on mortality and its modifiers in China: an analysis from 66 communities.

    Science.gov (United States)

    Ma, Wenjun; Zeng, Weilin; Zhou, Maigeng; Wang, Lijun; Rutherford, Shannon; Lin, Hualiang; Liu, Tao; Zhang, Yonghui; Xiao, Jianpeng; Zhang, Yewu; Wang, Xiaofeng; Gu, Xin; Chu, Cordia

    2015-02-01

    Many studies have reported increased mortality risk associated with heat waves. However, few have assessed the health impacts at a nation scale in a developing country. This study examines the mortality effects of heat waves in China and explores whether the effects are modified by individual-level and community-level characteristics. Daily mortality and meteorological variables from 66 Chinese communities were collected for the period 2006-2011. Heat waves were defined as ≥2 consecutive days with mean temperature ≥95th percentile of the year-round community-specific distribution. The community-specific mortality effects of heat waves were first estimated using a Distributed Lag Non-linear Model (DLNM), adjusting for potential confounders. To investigate effect modification by individual characteristics (age, gender, cause of death, education level or place of death), separate DLNM models were further fitted. Potential effect modification by community characteristics was examined using a meta-regression analysis. A total of 5.0% (95% confidence intervals (CI): 2.9%-7.2%) excess deaths were associated with heat waves in 66 Chinese communities, with the highest excess deaths in north China (6.0%, 95% CI: 1%-11.3%), followed by east China (5.2%, 95% CI: 0.4%-10.2%) and south China (4.5%, 95% CI: 1.4%-7.6%). Our results indicate that individual characteristics significantly modified heat waves effects in China, with greater effects on cardiovascular mortality, cerebrovascular mortality, respiratory mortality, the elderly, females, the population dying outside of a hospital and those with a higher education attainment. Heat wave mortality effects were also more pronounced for those living in urban cities or densely populated communities. Heat waves significantly increased mortality risk in China with apparent spatial heterogeneity, which was modified by some individual-level and community-level factors. Our findings suggest adaptation plans that target vulnerable

  12. Thermal substitution and aerobic efficiency: measuring and predicting effects of heat balance on endotherm diving energetics.

    Science.gov (United States)

    Lovvorn, J R

    2007-11-29

    For diving endotherms, modelling costs of locomotion as a function of prey dispersion requires estimates of the costs of diving to different depths. One approach is to estimate the physical costs of locomotion (Pmech) with biomechanical models and to convert those estimates to chemical energy needs by an aerobic efficiency (eta=Pmech/Vo2) based on oxygen consumption (Vo2) in captive animals. Variations in eta with temperature depend partly on thermal substitution, whereby heat from the inefficiency of exercising muscles or the heat increment of feeding (HIF) can substitute for thermogenesis. However, measurements of substitution have ranged from lack of detection to nearly complete use of exercise heat or HIF. This inconsistency may reflect (i) problems in methods of calculating substitution, (ii) confounding mechanisms of thermoregulatory control, or (iii) varying conditions that affect heat balance and allow substitution to be expressed. At present, understanding of how heat generation is regulated, and how heat is transported among tissues during exercise, digestion, thermal challenge and breath holding, is inadequate for predicting substitution and aerobic efficiencies without direct measurements for conditions of interest. Confirming that work rates during exercise are generally conserved, and identifying temperatures at those work rates below which shivering begins, may allow better prediction of aerobic efficiencies for ecological models.

  13. Energy-efficiency in inductive heating of forging ingots; Energieeffizienz bei der induktiven Erwaermung von Schmiedebloecken

    Energy Technology Data Exchange (ETDEWEB)

    Padberg, Michael; Doetsch, Erwin [ABP Induction Systems, Dortmund (Germany)

    2012-03-15

    The continuously increasing importance of the CO{sub 2} balance and of conservation of resources is resulting in ever greater demands for high energy-efficiency in the process used for heating of forging ingots. Plant and process engineering play roles of parallel significance in the fulfillment of these requirements, and this article focuses on both in equal degree. The shares of the individual components in the overall energy consumption of an induction heating installation are therefore firstly determined, and their respective potentials for optimization then discussed. The quality of the heating process itself, and its optimum design for reduction of energy consumption, are then examined. (orig.)

  14. Development of an Efficient GPU-Accelerated Model for Fully Nonlinear Water Waves

    DEFF Research Database (Denmark)

    of an optimized sequential single-CPU algorithm based on a flexible-order Finite Difference Method. High performance is pursued by utilizing many-core processing in the model focusing on GPUs for acceleration of code execution. This involves combining analytical methods with an algorithm redesign of the current......This work is concerned with the development of an efficient high-throughput scalable model for simulation of fully nonlinear water waves (OceanWave3D) applicable to solve and analyze large-scale problems in coastal engineering. The goal can be achieved through algorithm redesign and parallelization...... numerical model....

  15. Total energy concept (100% efficiency) applied to gas-fired heat generators

    Energy Technology Data Exchange (ETDEWEB)

    Rado, L.

    1976-01-01

    Tests carried out by Ruhrgas AG on a Recitherm unit have shown that the total energy concept can also be applied to general space-heating applications using relatively simple equipment. The concept--successfully used for many years in warming the water in swimming pools--can be extended to other heating applications. The Ruhrgas tests showed that the efficiency of the Recitherm unit varied between 91.3 and 91.9 percent, depending on the load factor of the heat generator if heat utilization is related to the gross calorific value. Converting this amount of energy utilization into the net calorific value, as generally done in evaluating heat generators, yields a theoretical efficiency of 101.2 and 101.9 percent, depending on the load factor. For space-heating systems, this results in heat-energy savings of about 14 percent. Recitherm units can today be used economically in conjunction with boilers rated at 0.8 million Btu (0.2 Gcal)/hr. Further development efforts by the manufacturer will delineate the economical limits of the unit.

  16. The role played by thermal feedback in heated Farley-Buneman waves at high latitudes

    Directory of Open Access Journals (Sweden)

    J.-P. St.-Maurice

    Full Text Available It is becoming increasingly clear that electron thermal effects have to be taken into account when dealing with the theory of ionospheric instabilities in the high-latitude ionosphere. Unfortunately, the mathematical complexity often hides the physical processes at work. We follow the limiting cases of a complex but systematic generalized fluid approach to get to the heart of the thermal processes that affect the stability of E region waves during electron heating events. We try to show as simply as possible under what conditions thermal effects contribute to the destabilization of strongly field-aligned (zero aspect angle Farley-Buneman modes. We show that destabilization can arise from a combination of (1 a reduction in pressure gradients associated with temperature fluctuations that are out of phase with density fluctuations, and (2 thermal diffusion, which takes the electrons from regions of enhanced temperatures to regions of negative temperature fluctuations, and therefore enhanced densities. However, we also show that, contrary to what has been suggested in the past, for modes excited along the E0×B direction thermal feedback decreases the growth rate and raises the threshold speed of the Farley-Buneman instability. The increase in threshold speed appears to be important enough to explain the generation of `Type IV' waves in the high-latitude ionosphere.

    Key words: Ionosphere (auroral ionosphere; iono- spheric irregularities; plasma waves and instabilities

  17. The role played by thermal feedback in heated Farley-Buneman waves at high latitudes

    Directory of Open Access Journals (Sweden)

    J.-P. St.-Maurice

    2000-05-01

    Full Text Available It is becoming increasingly clear that electron thermal effects have to be taken into account when dealing with the theory of ionospheric instabilities in the high-latitude ionosphere. Unfortunately, the mathematical complexity often hides the physical processes at work. We follow the limiting cases of a complex but systematic generalized fluid approach to get to the heart of the thermal processes that affect the stability of E region waves during electron heating events. We try to show as simply as possible under what conditions thermal effects contribute to the destabilization of strongly field-aligned (zero aspect angle Farley-Buneman modes. We show that destabilization can arise from a combination of (1 a reduction in pressure gradients associated with temperature fluctuations that are out of phase with density fluctuations, and (2 thermal diffusion, which takes the electrons from regions of enhanced temperatures to regions of negative temperature fluctuations, and therefore enhanced densities. However, we also show that, contrary to what has been suggested in the past, for modes excited along the E0×B direction thermal feedback decreases the growth rate and raises the threshold speed of the Farley-Buneman instability. The increase in threshold speed appears to be important enough to explain the generation of `Type IV' waves in the high-latitude ionosphere.Key words: Ionosphere (auroral ionosphere; iono- spheric irregularities; plasma waves and instabilities

  18. Risk factors for deaths during the 2009 heat wave in Adelaide, Australia: a matched case-control study

    Science.gov (United States)

    Zhang, Ying; Nitschke, Monika; Krackowizer, Antoinette; Dear, Keith; Pisaniello, Dino; Weinstein, Philip; Tucker, Graeme; Shakib, Sepehr; Bi, Peng

    2017-01-01

    The extreme heat wave in Australia in 2009 resulted in significantly increased number of daily deaths. The circumstances that lead to deaths during extreme heat have not been explored before in Australia. This study aims to identify the individual and community risk factors for deaths during this extreme heat wave in Adelaide. A matched case-control study was conducted. Cases were those who died in the Adelaide metropolitan area during the heat wave period. For each case, two community controls were randomly selected, matched by age and gender. Face-to-face or telephone interviews were conducted to collect data of demographic information, living environment, social support, health status and behavioural changes during the heat wave. Descriptive analysis, as well as simple and multiple conditional logistic regressions were performed. In total, 82 deaths and 164 matched community controls were included in the analysis, with a median age of 77.5 (range 26.6-100.7). The multiple logistic regression model indicated that, compared with controls, the risk of death during the heat wave was significantly increased for people living alone (AOR = 42.31, 95 % CI 2.3, 792.8) or having existing chronic heart disease (AOR = 22.4, 95 % CI 1.7, 303.0). In addition, having air conditioning in bedrooms (AOR = 0.004, 95 % CI 0.00006, 0.28) and participating in social activities more than once a week (AOR = 0.011, 95 % CI 0.0004, 0.29) indicated significant protective effects. We have identified factors that could significantly impact on the likelihood of deaths during heat waves. Our findings could assist in the development of future intervention programs and policies to reduce mortality associated with a warmer climate.

  19. Attributing human mortality during extreme heat waves to anthropogenic climate change

    Science.gov (United States)

    Mitchell, Daniel; Heaviside, Clare; Vardoulakis, Sotiris; Huntingford, Chris; Masato, Giacomo; Guillod, Benoit P.; Frumhoff, Peter; Bowery, Andy; Wallom, David; Allen, Myles

    2016-07-01

    It has been argued that climate change is the biggest global health threat of the 21st century. The extreme high temperatures of the summer of 2003 were associated with up to seventy thousand excess deaths across Europe. Previous studies have attributed the meteorological event to the human influence on climate, or examined the role of heat waves on human health. Here, for the first time, we explicitly quantify the role of human activity on climate and heat-related mortality in an event attribution framework, analysing both the Europe-wide temperature response in 2003, and localised responses over London and Paris. Using publicly-donated computing, we perform many thousands of climate simulations of a high-resolution regional climate model. This allows generation of a comprehensive statistical description of the 2003 event and the role of human influence within it, using the results as input to a health impact assessment model of human mortality. We find large-scale dynamical modes of atmospheric variability remain largely unchanged under anthropogenic climate change, and hence the direct thermodynamical response is mainly responsible for the increased mortality. In summer 2003, anthropogenic climate change increased the risk of heat-related mortality in Central Paris by ∼70% and by ∼20% in London, which experienced lower extreme heat. Out of the estimated ∼315 and ∼735 summer deaths attributed to the heatwave event in Greater London and Central Paris, respectively, 64 (±3) deaths were attributable to anthropogenic climate change in London, and 506 (±51) in Paris. Such an ability to robustly attribute specific damages to anthropogenic drivers of increased extreme heat can inform societal responses to, and responsibilities for, climate change.

  20. Strained-graphene-based highly efficient quantum heat engine operating at maximum power

    Science.gov (United States)

    Mani, Arjun; Benjamin, Colin

    2017-09-01

    A strained graphene monolayer is shown to operate as a highly efficient quantum heat engine delivering maximum power. The efficiency and power of the proposed device exceeds that of recent proposals. The reason for these excellent characteristics is that strain enables complete valley separation in transmittance through the device, implying that increasing strain leads to very high Seebeck coefficient as well as lower conductance. In addition, since time-reversal symmetry is unbroken in our system, the proposed strained graphene quantum heat engine can also act as a high-performance refrigerator.

  1. The universal power and efficiency characteristics for irreversible reciprocating heat engine cycles

    CERN Document Server

    Qin Xiao Yong; Sun Feng Rui; Wu Chih

    2003-01-01

    The performance of irreversible reciprocating heat engine cycles with heat transfer loss and friction-like term loss is analysed using finite-time thermodynamics. The universal relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, and the optimal relation between power output and the efficiency of the cycles are derived. Moreover, analysis and optimization of the model were carried out in order to investigate the effect of cycle processes on the performance of the cycle using numerical examples. The results obtained herein include the performance characteristics of irreversible reciprocating Diesel, Otto, Atkinson and Brayton cycles.

  2. Efficient non-hydrostatic modelling of 3D wave-induced currents using a subgrid approach

    Science.gov (United States)

    Rijnsdorp, Dirk P.; Smit, Pieter B.; Zijlema, Marcel; Reniers, Ad J. H. M.

    2017-08-01

    Wave-induced currents are an ubiquitous feature in coastal waters that can spread material over the surf zone and the inner shelf. These currents are typically under resolved in non-hydrostatic wave-flow models due to computational constraints. Specifically, the low vertical resolutions adequate to describe the wave dynamics - and required to feasibly compute at the scales of a field site - are too coarse to account for the relevant details of the three-dimensional (3D) flow field. To describe the relevant dynamics of both wave and currents, while retaining a model framework that can be applied at field scales, we propose a two grid approach to solve the governing equations. With this approach, the vertical accelerations and non-hydrostatic pressures are resolved on a relatively coarse vertical grid (which is sufficient to accurately resolve the wave dynamics), whereas the horizontal velocities and turbulent stresses are resolved on a much finer subgrid (of which the resolution is dictated by the vertical scale of the mean flows). This approach ensures that the discrete pressure Poisson equation - the solution of which dominates the computational effort - is evaluated on the coarse grid scale, thereby greatly improving efficiency, while providing a fine vertical resolution to resolve the vertical variation of the mean flow. This work presents the general methodology, and discusses the numerical implementation in the SWASH wave-flow model. Model predictions are compared with observations of three flume experiments to demonstrate that the subgrid approach captures both the nearshore evolution of the waves, and the wave-induced flows like the undertow profile and longshore current. The accuracy of the subgrid predictions is comparable to fully resolved 3D simulations - but at much reduced computational costs. The findings of this work thereby demonstrate that the subgrid approach has the potential to make 3D non-hydrostatic simulations feasible at the scale of a

  3. On exact solutions of a heat-wave type with logarithmic front for the porous medium equation

    Science.gov (United States)

    Kazakov, A. L.; Lempert, A. A.; Orlov, S. S.; Orlov, S. S.

    2017-10-01

    The paper deals with a nonlinear second-order parabolic equation with partial derivatives, which is usually called “the porous medium equation”. It describes the processes of heat and mass transfer as well as filtration of liquids and gases in porous media. In addition, it is used for mathematical modeling of growth and migration of population. Usually this equation is studied numerically like most other nonlinear equations of mathematical physics. So, the construction of exact solution in an explicit form is important to verify the numerical algorithms. The authors deal with a special solutions which are usually called “heat waves”. A new class of heat-wave type solutions of one-dimensional (plane-symmetric) porous medium equation is proposed and analyzed. A logarithmic heat wave front is studied in details. Considered equation has a singularity at the heat wave front, because the factor of the highest (second) derivative vanishes. The construction of these exact solutions reduces to the integration of a nonlinear second-order ordinary differential equation (ODE). Moreover, the Cauchy conditions lead us to the fact that this equation has a singularity at the initial point. In other words, the ODE inherits the singularity of the original problem. The qualitative analysis of the solutions of the ODE is carried out. The obtained results are interpreted from the point of view of the corresponding heat waves’ behavior. The most interesting is a damped solitary wave, the length of which is constant, and the amplitude decreases.

  4. A consistent thermodynamics of the MHD wave-heated two-fluid solar wind

    Directory of Open Access Journals (Sweden)

    I. V. Chashei

    2003-07-01

    Full Text Available We start our considerations from two more recent findings in heliospheric physics: One is the fact that the primary solar wind protons do not cool off adiabatically with distance, but appear to be heated. The other one is that secondary protons, embedded in the solar wind as pick-up ions, behave quasi-isothermal at their motion to the outer heliosphere. These two phenomena must be physically closely connected with each other. To demonstrate this we solve a coupled set of enthalpy flow conservation equations for the two-fluid solar wind system consisting of primary and secondary protons. The coupling of these equations comes by the heat sources that are relevant, namely the dissipation of MHD turbulence power to the respective protons at the relevant dissipation scales. Hereby we consider both the dissipation of convected turbulences and the dissipation of turbulences locally driven by the injection of new pick-up ions into an unstable mode of the ion distribution function. Conversion of free kinetic energy of freshly injected secondary ions into turbulence power is finally followed by partial reabsorption of this energy both by primary and secondary ions. We show solutions of simultaneous integrations of the coupled set of differential thermodynamic two-fluid equations and can draw interesting conclusions from the solutions obtained. We can show that the secondary proton temperature with increasing radial distance asymptotically attains a constant value with a magnitude essentially determined by the actual solar wind velocity. Furthermore, we study the primary proton temperature within this two-fluid context and find a polytropic behaviour with radially and latitudinally variable polytropic indices determined by the local heat sources due to dissipated turbulent wave energy. Considering latitudinally variable solar wind conditions, as published by McComas et al. (2000, we also predict latitudinal variations of primary proton temperatures at

  5. A consistent thermodynamics of the MHD wave-heated two-fluid solar wind

    Directory of Open Access Journals (Sweden)

    I. V. Chashei

    Full Text Available We start our considerations from two more recent findings in heliospheric physics: One is the fact that the primary solar wind protons do not cool off adiabatically with distance, but appear to be heated. The other one is that secondary protons, embedded in the solar wind as pick-up ions, behave quasi-isothermal at their motion to the outer heliosphere. These two phenomena must be physically closely connected with each other. To demonstrate this we solve a coupled set of enthalpy flow conservation equations for the two-fluid solar wind system consisting of primary and secondary protons. The coupling of these equations comes by the heat sources that are relevant, namely the dissipation of MHD turbulence power to the respective protons at the relevant dissipation scales. Hereby we consider both the dissipation of convected turbulences and the dissipation of turbulences locally driven by the injection of new pick-up ions into an unstable mode of the ion distribution function. Conversion of free kinetic energy of freshly injected secondary ions into turbulence power is finally followed by partial reabsorption of this energy both by primary and secondary ions. We show solutions of simultaneous integrations of the coupled set of differential thermodynamic two-fluid equations and can draw interesting conclusions from the solutions obtained. We can show that the secondary proton temperature with increasing radial distance asymptotically attains a constant value with a magnitude essentially determined by the actual solar wind velocity. Furthermore, we study the primary proton temperature within this two-fluid context and find a polytropic behaviour with radially and latitudinally variable polytropic indices determined by the local heat sources due to dissipated turbulent wave energy. Considering latitudinally variable solar wind conditions, as published by McComas et al. (2000, we also predict latitudinal variations of primary proton temperatures at

  6. Spatial Approach of Climate Risk Assessment and Uncertainty: A Case Study of Heat Wave Risk in Seoul

    Science.gov (United States)

    Ahn, S.; Lee, D. K.; Jeong, W.

    2016-12-01

    As climate change continuously reaches new climaxes, it is aggravating many climate extremes. Urban heat island effect (UHI) is one of them. It occurs in cities with sealed surfaces and building canyons, which make changes in storage, radiative and turbulent heat flux that make cities warmer than surrounding areas. However, applying adequate policies at the right place can attenuate the impacts of UHI. Therefore, heat wave risk assessment is important in the sense that it helps decision makers set priority in targets of application. Seoul is highly urbanized capital of South Korea. It is suffering from increasing heat wave days and tropical nights every year. More than 10 million residents are exposed to heat extremes and measures should be taken. Therefore, heat wave risk assessment of Seoul should be done in advance. While, risk assessment contains uncertainty; from variables to assessment procedure. However, there is no standardized assessment methodology. A fuzzy logic, introduced by Zadeh in 1965, is applied in quantifying these uncertainties. We fuzzified indices for assessing heat wave risk with threshold values. And indices were aggregated step by step with fuzzy operators, which make up "vulnerability" and "climate exposure". Vulnerability and climate exposure are further combined with fuzzy operator to derive complete heat wave risk assessment map. As a result, we expressed spatial distribution of UHI risk. Districts lying in the central area of the city showed higher risk than in marginal areas. In addition, hierarchic structured approach of assessing risk in this study makes it easy to track key variables of risk, therefore, giving decision makers insights to help their application of adaptation policies.

  7. Economical Efficiency of Combined Cooling Heating and Power Systems Based on an Enthalpy Method

    Directory of Open Access Journals (Sweden)

    Yan Xu

    2017-11-01

    Full Text Available As the living standards of Chinese people have been improving, the energy demand for cooling and heating, mainly in the form of electricity, has also expanded. Since an integrated cooling, heating and power supply system (CCHP will serve this demand better, the government is now attaching more importance to the application of CCHP energy systems. Based on the characteristics of the combined cooling heating and power supply system, and the method of levelized cost of energy, two calculation methods for the evaluation of the economical efficiency of the system are employed when the energy production in the system is dealt with from the perspective of exergy. According to the first method, fuel costs account for about 75% of the total cost. In the second method, the profits from heating and cooling are converted to fuel costs, resulting in a significant reduction of fuel costs, accounting for 60% of the total cost. Then the heating and cooling parameters of gas turbine exhaust, heat recovery boiler, lithium-bromide heat-cooler and commercial tariff of provincial capitals were set as benchmark based on geographic differences among provinces, and the economical efficiency of combined cooling heating and power systems in each province were evaluated. The results shows that the combined cooling heating and power system is economical in the developed areas of central and eastern China, especially in Hubei and Zhejiang provinces, while in other regions it is not. The sensitivity analysis was also made on related influencing factors of fuel cost, demand intensity in heating and cooling energy, and bank loans ratio. The analysis shows that the levelized cost of energy of combined cooling heating and power systems is very sensitive to exergy consumption and fuel costs. When the consumption of heating and cooling energy increases, the unit cost decreases by 0.1 yuan/kWh, and when the on-grid power ratio decreases by 20%, the cost may increase by 0.1 yuan

  8. Awareness of and Attitudes towards Heat Waves within the Context of Climate Change among a Cohort of Residents in Adelaide, Australia

    Science.gov (United States)

    Akompab, Derick A.; Bi, Peng; Williams, Susan; Grant, Janet; Walker, Iain A.; Augoustinos, Martha

    2012-01-01

    Heat waves are a public health concern in Australia and unprecedented heat waves have been recorded in Adelaide over recent years. The aim of this study was to examine the perception and attitudes towards heat waves in the context of climate change among a group of residents in Adelaide, an Australian city with a temperate climate. A cross-sectional study was conducted in the summer of 2012 among a sample of 267 residents. The results of the survey found that television (89.9%), radio (71.2%), newspapers (45.3%) were the main sources from which respondents received information about heat waves. The majority of the respondents (73.0%) followed news about heat waves very or somewhat closely. About 26.6% of the respondents were extremely or very concerned about the effects of heat waves on them personally. The main issues that were of personal concern for respondents during a heat wave were their personal comfort (60.7%), their garden (48.7%), and sleeping well (47.6%). Overall, respondents were more concerned about the impacts of heat waves to the society than on themselves. There was a significant association between gender (χ² = 21.2, df = 3, p = 0.000), gross annual household income (p = 0.03) and concern for the societal effects of heat waves. Less than half (43.2%) of the respondents believed that heat waves will extremely or very likely increase in Adelaide according to climate projections. Nearly half (49.3%) believed that the effects of heat waves were already being felt in Adelaide. These findings may inform the reframing and communication strategies for heat waves in Adelaide in the context of climate change. PMID:23343978

  9. Awareness of and Attitudes towards Heat Waves within the Context of Climate Change among a Cohort of Residents in Adelaide, Australia

    Directory of Open Access Journals (Sweden)

    Iain A. Walker

    2012-12-01

    Full Text Available Heat waves are a public health concern in Australia and unprecedented heat waves have been recorded in Adelaide over recent years. The aim of this study was to examine the perception and attitudes towards heat waves in the context of climate change among a group of residents in Adelaide, an Australian city with a temperate climate. A cross-sectional study was conducted in the summer of 2012 among a sample of 267 residents. The results of the survey found that television (89.9%, radio (71.2%, newspapers (45.3% were the main sources from which respondents received information about heat waves. The majority of the respondents (73.0% followed news about heat waves very or somewhat closely. About 26.6% of the respondents were extremely or very concerned about the effects of heat waves on them personally. The main issues that were of personal concern for respondents during a heat wave were their personal comfort (60.7%, their garden (48.7%, and sleeping well (47.6%. Overall, respondents were more concerned about the impacts of heat waves to the society than on themselves. There was a significant association between gender (χ² = 21.2, df = 3, p = 0.000, gross annual household income (p = 0.03 and concern for the societal effects of heat waves. Less than half (43.2% of the respondents believed that heat waves will extremely or very likely increase in Adelaide according to climate projections. Nearly half (49.3% believed that the effects of heat waves were already being felt in Adelaide. These findings may inform the reframing and communication strategies for heat waves in Adelaide in the context of climate change.

  10. Heat transfer and wall temperature effects in shock wave turbulent boundary layer interactions

    CERN Document Server

    Bernardini, Matteo; Pirozzoli, Sergio; Grasso, Francesco

    2016-01-01

    Direct numerical simulations are carried out to investigate the effect of the wall temperature on the behavior of oblique shock-wave/turbulent boundary layer interactions at freestream Mach number $2.28$ and shock angle of the wedge generator $\\varphi = 8^{\\circ}$. Five values of the wall-to-recovery-temperature ratio ($T_w/T_r$) are considered, corresponding to cold, adiabatic and hot wall thermal conditions. We show that the main effect of cooling is to decrease the characteristic scales of the interaction in terms of upstream influence and extent of the separation bubble. The opposite behavior is observed in the case of heating, that produces a marked dilatation of the interaction region. The distribution of the Stanton number shows that a strong amplification of the heat transfer occurs across the interaction, and the maximum values of thermal and dynamic loads are found in the case of cold wall. The analysis reveals that the fluctuating heat flux exhibits a strong intermittent behavior, characterized by ...

  11. Surface thermal analysis of North Brabant cities and neighbourhoods during heat waves

    Directory of Open Access Journals (Sweden)

    Leyre Echevarria Icaza

    2016-03-01

    Full Text Available The urban heat island effect is often associated with large metropolises. However, in the Netherlands even small cities will be affected by the phenomenon in the future (Hove et al., 2011, due to the dispersed or mosaic urbanisation patterns in particularly the southern part of the country: the province of North Brabant. This study analyses the average night time land surface temperature (LST of 21 North-Brabant urban areas through 22 satellite images retrieved by Modis 11A1 during the 2006 heat wave and uses Landsat 5 Thematic Mapper to map albedo and normalized difference temperature index (NDVI values. Albedo, NDVI and imperviousness are found to play the most relevant role in the increase of night-time LST. The surface cover cluster analysis of these three parameters reveals that the 12 “urban living environment” categories used in the region of North Brabant can actually be reduced to 7 categories, which simplifies the design guidelines to improve the surface thermal behaviour of the different neighbourhoods thus reducing the Urban Heat Island (UHI effect in existing medium size cities and future developments adjacent to those cities.

  12. Efficient protocols for Stirling heat engines at the micro-scale

    Science.gov (United States)

    Muratore-Ginanneschi, Paolo; Schwieger, Kay

    2015-10-01

    We investigate the thermodynamic efficiency of sub-micro-scale Stirling heat engines operating under the conditions described by overdamped stochastic thermodynamics. We show how to construct optimal protocols such that at maximum power the efficiency attains for constant isotropic mobility the universal law η=2 ηC/(4-ηC) , where ηC is the efficiency of an ideal Carnot cycle. We show that these protocols are specified by the solution of an optimal mass transport problem. Such solution can be determined explicitly using well-known Monge-Ampère-Kantorovich reconstruction algorithms. Furthermore, we show that the same law describes the efficiency of heat engines operating at maximum work over short time periods. Finally, we illustrate the straightforward extension of these results to cases when the mobility is anisotropic and temperature dependent.

  13. High efficiency off-axis current drive by high frequency fast waves

    Science.gov (United States)

    Prater, R.; Pinsker, R. I.; Moeller, C. P.; Porkolab, M.; Vdovin, V.

    2014-02-01

    Modeling work shows that current drive can be done off-axis with high efficiency, as required for FNSF and DEMO, by using very high harmonic fast waves ("helicons" or "whistlers"). The modeling indicates that plasmas with high electron beta are needed in order for the current drive to take place off-axis, making DIII-D a highly suitable test vehicle for this process. The calculations show that the driven current is not very sensitive to the launched value of n∥, a result that can be understood from examination of the evolution of n∥ as the waves propagate in the plasma. Because of this insensitivity, relatively large values (˜3) of n∥ can be launched, thereby avoiding some of the problems with mode conversion in the boundary found in some previous experiments. Use of a traveling wave antenna provides a very narrow n∥ spectrum, which also helps avoid mode conversion.

  14. Efficiency and cost analysis of a designed in-line water heating system compared to a conventional water heating system in South Africa

    OpenAIRE

    Gouws, Rupert; Le Roux, Estie

    2012-01-01

    In this paper, the authors compares the efficiency and cost of a designed in-line water heating system with a conventional water heating system (geyser) in South Africa. The paper provides an overview on water heating systems and heating elements and provides the typical water consumption required by an average household in South Africa. A summary on the design of the in-line water heating system together with a system cost analysis is provided. The designed in-line water heating system ta...

  15. Efficient techniques for wave-based sound propagation in interactive applications

    Science.gov (United States)

    Mehra, Ravish

    Sound propagation techniques model the effect of the environment on sound waves and predict their behavior from point of emission at the source to the final point of arrival at the listener. Sound is a pressure wave produced by mechanical vibration of a surface that propagates through a medium such as air or water, and the problem of sound propagation can be formulated mathematically as a second-order partial differential equation called the wave equation. Accurate techniques based on solving the wave equation, also called the wave-based techniques, are too expensive computationally and memory-wise. Therefore, these techniques face many challenges in terms of their applicability in interactive applications including sound propagation in large environments, time-varying source and listener directivity, and high simulation cost for mid-frequencies. In this dissertation, we propose a set of efficient wave-based sound propagation techniques that solve these three challenges and enable the use of wave-based sound propagation in interactive applications. Firstly, we propose a novel equivalent source technique for interactive wave-based sound propagation in large scenes spanning hundreds of meters. It is based on the equivalent source theory used for solving radiation and scattering problems in acoustics and electromagnetics. Instead of using a volumetric or surface-based approach, this technique takes an object-centric approach to sound propagation. The proposed equivalent source technique generates realistic acoustic effects and takes orders of magnitude less runtime memory compared to prior wave-based techniques. Secondly, we present an efficient framework for handling time-varying source and listener directivity for interactive wave-based sound propagation. The source directivity is represented as a linear combination of elementary spherical harmonic sources. This spherical harmonic-based representation of source directivity can support analytical, data

  16. Highly efficient square wave distant dipolar field and its application for in vivo MRI.

    Science.gov (United States)

    Cai, Congbo; Gao, Fenglian; Cai, Shuhui; Zhong, Jianhui; Chen, Zhong

    2010-10-01

    Intermolecular multiple quantum coherences generated by distant dipolar field (DDF) have some attractive properties, but the intrinsic weak signal intensity prevents their widespread applications. Recently, Branca et al. (J Chem Phys 2008;129:054502) suggested that square wave DDF was more efficient than conventional sinusoidal DDF because it could simultaneously produce intermolecular multiple quantum coherences signal with various major orders. In this article, instead of a series of adiabatic inversion pulses proposed previously, a more efficient composite adiabatic inversion pulse was applied to create square wave DDF. The square wave DDF was applied to in vivo MRI for the first time, and the corresponding simulations were performed. Both experimental and simulated results show that square wave DDF with composite adiabatic inversion pulse improves over the original Z-modulation enhanced to binary for self-refocused acquisition implementation and can enhance the signal intensity to about 2-fold of that from conventional correlation spectroscopy (COSY) revamped with asymmetric Z-gradient echo detection sequence for in vivo MRI, close to the theoretical prediction.

  17. The evaluation of energy efficiency of convective heat transfer surfaces in tube bundles

    Science.gov (United States)

    Grigoriev, B. A.; Pronin, V. A.; Salohin, V. I.; Sidenkov, D. V.

    2017-11-01

    When evaluating the effectiveness of the heat exchange surfaces in the main considered characteristics such as heat flow (Q, Watt), the power required for pumps (N, Watt), and surface area of heat transfer (F, m2). The most correct comparison provides a comparison “ceteris paribus”. Carried out performance comparison “ceteris paribus” in-line and staggered configurations of bundles with a circular pipes can serve as a basis for the development of physical models of flow and heat transfer in tube bundles with tubes of other geometric shapes, considering intertubular stream with attached eddies. The effect of longitudinal and transverse steps of the pipes on the energy efficiency of different configurations would take into account by mean of physical relations between the structure of shell side flow with attached eddies and intensity of transfer processes of heat and momentum. With the aim of energy-efficient placement of tubes, such an approach opens up great opportunities for the synthesis of a plurality of tubular heat exchange surfaces, in particular, the layout of the twisted and in-line-diffuser type with a drop-shaped pipes.

  18. Flexible thermoelectric generator with efficient vertical to lateral heat path films

    Science.gov (United States)

    Nishino, T.; Suzuki, T.

    2017-03-01

    This paper presents a flexible thermoelectric generator (TEG) with heat path films, which efficiently convert vertical temperature difference (ΔT) into lateral ΔT for thermocouple (TC). The heat path film consists of copper-filled-vias with low thermal resistance and polymer films with high thermal resistance. They were made in two fabrication steps. The first used a flexible printed circuit board with high density copper-filled-vias, while the second saw the deposition of thin film TCs. The combination offers flexibility of application due to its thinness, mass production potential, and low energy heat loss in the device. We demonstrated 54 TCs cm-2 in a 25 cm2 flexible TEG using Bi2Te3- and Nickel-based TCs respectively. The experimental data were in good accordance with a model which was calculated using the finite element method. The prototype flexible TEGs indicated that the proposed structure converted 84% heat flow from vertical into lateral ΔT in each TC, which was two times higher than the non-heat path film. They produced voltage of 11 mV/K/cm2 and power output of 0.1 µW/K/cm2 respectively. These flexible TEGs are ideally suited for harvesting from waste heat emitted from objects with large wavy areas because of their low weight, low cost and high efficiency conversion with flexibility.

  19. An open source tool to analyse heat waves using flow analogues and weather regimes

    Science.gov (United States)

    Radanovics, Sabine; Jézéquel, Aglaé; Alvarez-Castro, Carmen; Yiou, Pascal; Hempelmann, Nils; Ehbrecht, Carsten; Nangini, Cathy; Vautard, Robert

    2017-04-01

    Studies on the relation of atmospheric circulation patterns and heat waves using flow analogues or weather regimes often miss an assessment of the uncertainties related to internal climate variability and the analysis method itself because of the limited length of the data sets used. However, considering this type of uncertainty is important when interpreting changes found in a transient climate using this type of methods. We used several hundreds of years long preindustrial control runs of CMIP5 climate models to address this issue in a constant model climate. Several heat waves over central Europe as simulated by the climate model were selected and then reconstructed using circulation analogues, that is by searching for days with similar pressure fields in the simulation and recombining the temperatures of these similar days to form uchronic events. The variance of these uchronic events is supposed to vary with the rarity of the original event. We therefore present the relationship between the variance of the uchronic events and the distance between the original event and its analogues. Further we present the variation of the distances due to internal climate variability. Weather regimes are typical atmospheric circulation patterns obtained for example using a cluster analysis. Each day is then assigned to a cluster, the weather regime. The frequency of the weather regimes is supposed to be constant in a constant climate, but variations of these frequencies can occur due to internal climate variability. We therefore show these variations for the weather regimes associated with the heat waves. The web processing service (WPS) flyingpigeon is an open source WPS featuring processes for studying weather extremes and climate change impacts. Flyingpigeon is part of the open source project birdhouse, a collection of WPSs following the Open Geospatial Consortium (OGC) standard and available on github. The WPS allowed to first select the data sets needed from the ESGF

  20. Development of a Millimeter-Wave Beam Position and Profile Monitor for Transmission Efficiency Improvement in an ECRH System

    Directory of Open Access Journals (Sweden)

    Shimozuma T.

    2015-01-01

    Full Text Available In a high power Electron Cyclotron Resonance Heating (ECRH system, a long-distance and low-loss transmission system is required to realize effective heating of nuclear fusion-relevant plasmas. A millimeter-wave beam position and profile monitor, which can be used in a high-power, evacuated, and cooled transmission line, is proposed, designed, manufactured, and tested. The beam monitor consists of a reflector, Peltier-device array and a heat-sink. It was tested using simulated electric heater power or gyrotron output power. The data obtained from the monitor were well agreed with the heat source position and profile. The methods of data analysis and mode-content analysis of a propagating millimeter-wave in the corrugated wave-guide are proposed.

  1. Efficiency at maximum power of a quantum heat engine based on two coupled oscillators.

    Science.gov (United States)

    Wang, Jianhui; Ye, Zhuolin; Lai, Yiming; Li, Weisheng; He, Jizhou

    2015-06-01

    We propose and theoretically investigate a system of two coupled harmonic oscillators as a heat engine. We show how these two coupled oscillators within undamped regime can be controlled to realize an Otto cycle that consists of two adiabatic and two isochoric processes. During the two isochores the harmonic system is embedded in two heat reservoirs at constant temperatures T(h) and T(c)(heat engine, we adopt the semigroup approach to model the thermal relaxation dynamics along the two isochoric processes, and we find the upper bound of efficiency at maximum power (EMP) η* to be a function of the Carnot efficiency η(C)(=1-T(c)/T(h)): η*≤η(+)≡η(C)(2)/[η(C)-(1-η(C))ln(1-η(C))], identical to those previously derived from ideal (noninteracting) microscopic, mesoscopic, and macroscopic systems.

  2. Fuel Application Efficiency in Ideal Cycle of Gas Turbine Plant with Isobaric Heat Supply

    Directory of Open Access Journals (Sweden)

    A. P. Nesenchuk

    2013-01-01

    Full Text Available The paper reveals expediency to use in prospect fuels with maximum value  Qнр∑Vi and minimum theoretical burning temperature in order to obtain maximum efficiency of the ideal cycle in GTP with isobaric heat supply.

  3. IMPACTS OF REFRIGERANTLINE LENGTH ON SYSTEM EFFICIENCY IN RESIDENTIAL HEATING AND COOLING SYSTEMS USING REFRIGERANT DISTRIBUTION.

    Energy Technology Data Exchange (ETDEWEB)

    ANDREWS, J.W.

    2001-04-01

    The effects on system efficiency of excess refrigerant line length are calculated for an idealized residential heating and cooling system. By excess line length is meant refrigerant tubing in excess of the 25 R provided for in standard equipment efficiency test methods. The purpose of the calculation is to provide input for a proposed method for evaluating refrigerant distribution system efficiency. A refrigerant distribution system uses refrigerant (instead of ducts or pipes) to carry heat and/or cooling effect from the equipment to the spaces in the building in which it is used. Such systems would include so-called mini-splits as well as more conventional split systems that for one reason or another have the indoor and outdoor coils separated by more than 25 ft. This report performs first-order calculations of the effects on system efficiency, in both the heating and cooling modes, of pressure drops within the refrigerant lines and of heat transfer between the refrigerant lines and the space surrounding them.

  4. High efficient ammonia heat pump system for industrial process water using the ISEC concept. Part 1

    DEFF Research Database (Denmark)

    Rothuizen, Erasmus Damgaard; Madsen, C.; Elmegaard, Brian

    2014-01-01

    The purpose of the Isolated System Energy Charging (ISEC) is to provide a high-efficient ammonia heat pump system for hot water production. The ISEC concept uses two storage tanks for the water, one discharged and one charged. The charged tank is used for the industrial process while the discharg...

  5. Efficiency gains of photovoltaic system using latent heat thermal energy storage

    NARCIS (Netherlands)

    Tan, Lippong; Date, Abhijit; Fernandes, Gabriel; Singh, Baljit; Ganguly, Sayantan

    This paper presents experimental assessments of the thermal and electrical performance of photovoltaic (PV) system by comparing the latent heat-cooled PV panel with the naturally-cooled equivalent. It is commonly known that the energy conversion efficiency of the PV cells declines with the increment

  6. Quick assessment of binary distillation efficiency using a heat engine perspective

    NARCIS (Netherlands)

    Blahusiak, Marek; Kiss, Anton Alexandru; Kersten, Sascha R.A.; Schuur, Boelo

    2016-01-01

    With emphasis on close boiling, (near-)ideal VLE mixtures, this paper links the efficiency of distillation to the binary feed composition and thermal properties of the compounds. The proposed approach, treating the process as a heat engine, allows to directly quantify distillation performance (in

  7. Efficiency evaluation for the heat pump system in sharp continental climate

    Directory of Open Access Journals (Sweden)

    Maksimov Vyacheslav I.

    2017-01-01

    Full Text Available With the aim to calculate the energy efficient of water source heat pump system (HPSW under sharp climate conditions, the ice formation processe on the surface of evaporator pipes under conditions of “autumn-winter-spring” was studied.

  8. Impact of boreal summer intraseasonal oscillation on heat wave occurrence in Asia and Europe during the summer of 2016

    Science.gov (United States)

    Lee, June-Yi; Hsu, Pang-Chi; ha, Kyung-Ja; Kim, Hae-Jeong; Jung, Yoo-Rim

    2017-04-01

    The summer of 2016 was the earth's hottest summer on record since 1880. Especially, in August, the global mean temperature was 1.66 degree higher than normal and heat waves set records across Asia, Europe, and North America. This study proposes that boreal summer intraseasonal oscillation (BSISO) played an important role in heat wave outbreaks over many regions of the Northern Hemisphere (NH) extratropics in the summer 2016 in addition to other factors including global warming, atmosphere-land interaction, and Africa-Pakistan heavy rainfall. By utilizing the real-time multivariate BSISO indices recently proposed, it has been demonstrated that the two dominant BSISO modes significantly modulate occurrence probability and spatial distributions of extreme rainfall and heat wave over Asia and Europe depending on their phases. The BSISO1 represents the canonical northward propagating variability that often occurs in conjunction with the eastward propagating Madden-Julian Oscillation with quasi-oscillating periods of 30-60 days. The BSISO2 represents the northward/northwestward propagating variability with periods of 10-30 days during primarily the pre-monsoon and monsoon-onset season. In August of 2016, BSISO1 was very active with amplitude up to 2 standard deviation and stayed at phase 7 state for about 20 days. During the phase 7 of BSISO1, extreme convective activity over the South China Sea and western North Pacific typically exerts significant global teleconnection leading to heat wave occurrence over East Asia including Korea and Japan, some part of Russia and Europe, and the western and eastern part of North America. In particular, anticyclonic circulation anomaly tends to be developed over East Asia inducing enhanced adiabatic and diabatic warming over Korea and Japan providing a favorable condition for extreme heat wave occurrence. The August of 2016 exhibited the typical global teleconnection pattern of BSISO1 associated with active convection over the western

  9. Full-wave and Fokker Planck analysis of ICRF heating experiments in the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Bonoli, P.T.; Golovato, S.; Porkolab, M.; Takase, Y. [MIT Plasma Fusion Center, Cambridge, MA (United States)

    1996-12-31

    The Alcator C-Mod device is a high field, high density, shaped tokamak with parameters a = 0.22 m, R{sub 0} = 0.67 m, B{sub 0} {le} 9.0 T, {kappa} {le} 1.8, {delta} {le} 0.8, and 1.0 x 10{sup 20} m{sup -3} n{sub e} (0) {le} 1.0 x 10{sup 21} m{sup -3}. Four megawatt of ICRF power is available at 80 MHz. The wide operating range in magnetic field makes several heating schemes possible: (i) Second harmonic heating of hydrogen (f{sub